About K Ring

Everything you need to know about your contactless payment ring and the company behind it

What is K Ring?

K Ring (formerly known as Kerv Ring) is the world’s first Mastercard® contactless payment ring … and the first in an innovative range of next-generation wearable payment devices.

K Ring can be used to make a payment anywhere in the world that accepts standard contactless credit, debit and prepaid card payments.

K Ring uses similar technology to that which is in the contactless payment cards already in your wallet or purse, but we’ve obviously had to make an innovative leap or two to make that technology work as an attractive and comfortable wearable device.

In addition to making payments with a single gesture, K Ring also facilitates one-touch access to public transport networks.

How do I make a payment with my K Ring?

To make a payment with your K Ring, just make a “knocking” gesture over the contactless card reader.

You will hear a beep and see a green light to signify a successful transaction. You don’t need to enter a PIN for payments made in the UK (current contactless payment limit is £30), but you may be asked to enter a PIN abroad, especially for higher-value transactions.

Where can I pay with my K Ring?

K Ring can be used to make a payment anywhere in the world that accepts Mastercard contactless payments. This includes stores, restaurants, bars, cafes, cinemas, taxis and some public transport networks – just look out for the contactless payments symbol below.

Can I make accidental payments with my K Ring?

No. K Ring can only make a payment if it’s within 4cm of a contactless payment terminal, when your hand in is the Transmission Ready Position.

Also, transactions must be initiated by the retailer, which means that the contactless card readers are inactive until payment is specifically requested.

How do I use K Ring on public transport?

At the moment, we can only offer information about using K Ring on the Transport for London network, where it can be used as a replacement for a ticket or Oyster Card.

You can use K Ring to pay as you go on bus, Tube, trams, DLR, London Overground, TfL Rail, Emirates Air Line, Thames Clipper River Bus and most National Rail services in London.

You use K Ring on the TfL network in the same way in which you make a contactless payment, by “knocking” on the yellow Oyster Card reader pad. Ensure you hold the ring over the centre of the yellow pad, and wait until the reader beeps.

If you use K Ring on London’s public transport network, you’ll benefit not just from a daily cap, but also from a Monday to Sunday weekly cap, which means that it will never cost you more than a daily or weekly travelcard.  

However, it’s important to note that the cap runs Monday to Sunday, so if you were going to make many journeys in London over a seven day period that started on a day other than Monday, a weekly Oyster travelcard could be slightly cheaper... but much less convenient!

Can I use my K Ring abroad?

Yes: anywhere in the world that accepts Mastercard® contactless payments - currently over 6 million locations worldwide.

If your K Ring is linked to our Virtual Prepaid Mastercard account, we use Mastercard’s foreign exchange rate, and any associated fees can be found in our Limits and Fees table.

As we use Mastercard’s foreign exchange rates, you may notice a slight difference in amount between the point when you make the transaction and when the charge is finalised with Mastercard, which could be up to two days later; this may show on your statement as an End of Day Balance Adjustment.

If your K Ring is linked directly to your bank account (currently only available to ABN AMRO customers), then your bank account’s rates and charges will apply as usual and we will not charge any additional fees.

Is there a transaction limit with my K Ring?

The transaction limit for a single contactless payment in the UK is currently £30, with a maximum allowed single transaction of (the equivalent of) £100 outside the UK.

If your K Ring is linked to our Virtual Prepaid Mastercard account, you can make up to 50 transactions per day with K Ring. On the Standard account you can spend up to £3,000 per day with your K Ring and on the Lite account, up to a total of £750 per day.

If your K Ring is linked directly to your bank account (currently only available to ABN AMRO customers), then your bank account’s contactless transaction limits will apply.

Will I still get my usual loyalty points/rewards when I pay with my K Ring?

If your K Ring is linked to our Virtual Prepaid Mastercard account and you load it using a card with which you collect loyalty points or receive cashback, you may still receive these, as a load will be categorised as a payment to K Wearables Ltd.

This is dependant on your particular card issuer and we recommend checking with them.

If your K Ring is linked directly to your bank account (currently only available to ABN AMRO customers), then you will continue to collect points or rewards as determined by your bank account’s terms and conditions.

How secure is my K Ring?

As K Ring uses the same technology as a contactless debit card, transactions made your ring are just as secure as a traditional contactless card payment. Furthermore, to make a payment with K Ring, it must be within very close proximity to a contactless reader and your hand must be in the Transmission Ready position to avoid any unintended transfer of data or funds.

Contactless transactions with K Ring over the Mastercard network are just as secure as using Chip & PIN. Your transactional data is always encrypted and because K Ring never leaves your finger, the risk of cloning or theft is significantly reduced.

If your K Ring is linked to a K Wearables Virtual Prepaid Mastercard account, you are protected by the stringent rules of the FCA; K Ring also provides you with all the tools you need to add further layers of security to your transactions, such as:

  • The ability to switch your ring on and off, anytime, anywhere
  • Constant background transactional risk assessments
  • Balance notifications

Why don’t I have to charge my K Ring?

K Ring contains no battery and therefore never needs charging. K Ring draws its power from the card reader during a contactless payment via electromagnetic induction.

Why don’t I have to pair my K Ring with my phone?

K Ring contains all the technology required to directly connect with the Mastercard payment network, so it doesn’t need to be paired with a smartphone to make a payment; it just works all by itself.

Is my K Ring waterproof?

Yes! The inner band of K Ring is made from a hard inert resin which seals the electronics and renders it completely waterproof.

How tough is my K Ring?

K Ring’s outer shell is made from zirconia ceramic (ZrO2), which is extremely hard and scratch resistant.

It is significantly harder and more scratch resistant than traditional metal jewellery – even that made of titanium. However, K Ring can still be damaged if dropped on a hard surface, or if a significant force is applied to it.

The table below provides context for K Ring’s scratch-resistance by showing where other common jewellery substances sit alongside zirconia ceramic on the Mohs scale of hardness:



Gold and silver

2.5 - 3


4 - 4.5



Zirconia ceramic


Corundum (rubies and sapphires)




Note: K Ring can easily be scratched by diamond rings or diamond-coated nail files / emery boards, so they must be kept separate at all times. We recommend that you do not wear a K Ring during nail care.

Will my K Ring irritate my skin?

K Ring’s inner band is made from an inert resin that has been specifically created with health and safety in mind, so it’s very unlikely that your K Ring will irritate your skin during normal usage.

If you do experience any discomfort or irritation, please let us know immediately by emailing support@mykring.com

Will my K Ring expire?

Yes, your K Ring will expire – much like a credit or debit card – 4 years after the date of issue.

We will alert you 30 days before your K Ring expires to give you plenty of opportunity to order a replacement.

How should I dispose of my K Ring?

If you no longer want your K Ring, or if it has expired, we ask that you return it to us (free of charge), rather than disposing of it as part of your household waste. We don’t want our products to contribute towards landfill, and the combination of materials means that it will be hard for you to recycle your K Ring yourself – so we’ll do it!

Contact support@mykring.com when you’re ready to dispose of your K Ring and we’ll take it from there.

Who makes the K Ring?

The K Wearables Prepaid Mastercard programme is operated by K Wearables Ltd, registered office: Regent House, 316 Beulah Hill, London, SE19 3HF. Company number 10093360; VAT registration number 258044208.

The K Wearables Prepaid Mastercard programme is issued by PSI-Pay Ltd pursuant to a license by Mastercard International Incorporated. PSI-Pay Ltd is authorised by the Financial Conduct Authority of the United Kingdom under the Electronic Money Regulations 2011 (register reference 900011) for the issuing of electronic money.

Is K Wearables authorised by the FCA in the UK?

Yes, via our e-money issuer, PSI-Pay Ltd, the company which issues the K Wearables Prepaid Mastercard. PSI-Pay Ltd is authorised by the Financial Conduct Authority of the United Kingdom under the Electronic Money Regulations 2011 (register reference 900011) for the issuing of electronic money.

How do I make a complaint?

We aim to rapidly resolve your complaint to your satisfaction so, in the first instance, please email us at complaints@myKring.com.

If you feel that we have not resolved your complaint to your satisfaction, you can ask for a review from the Financial Ombudsman Service (FOS), an independent and government-backed service designed to help complainants who find themselves in a dispute with a financial organisation. After reviewing your complaint, the FOS will make an adjudication on our response.

You can write to the FOS at:
Financial Ombudsman Service
Exchange Tower
E14 9SR

Or email them: complaint.info@financial-ombudsman.org.uk

Or call them: 0800 023 4567

Our Complaints Handling Procedure can be downloaded here.

For more information about the Financial Ombudsman Service, view an online version of their consumer leaflet or email us at complaints@myKring.com to request a copy by post.

How do I contact K Wearables?

Send us a message by selecting Help at the bottom of the screen


Or email us at: support@mykring.com

Write to us at:

K Wearables
Orion House
Bessemer Road
Welwyn Garden City

If your K Ring is lost or stolen, then call us immediately on 0844 502 0450.

How is K Wearables associated with Mastercard?

The K Wearables Prepaid Mastercard programme is issued by PSI-Pay Ltd under license from Mastercard.

Mastercard has formally issued a contactless vendor product letter of approval for the K Ring contactless payment ring, as an M/Chip Advance Payment and Data Storage device.

What do I do if I lose my K Ring, or if it’s stolen?

If you you’ve lost your K Ring but think you might find it again, log into your account at mykring.com, go to Devices and simply switch it off. This means your ring cannot be used to make a transaction. If you find it again, switch it on again in the same way.

If your K Ring is stolen, or if you don’t think you’re likely to find it again, call our Lost and Stolen hotline right away and we will permanently block your ring. Please note that this is irreversible, and that you will then have to buy a new K Ring, even if you eventually retrieve the one you’ve lost. Once your ring has been reported lost or stolen, you will not be liable for any fraudulent transactions made by a third party.

Lost and Stolen hotline: 0844 502 0450

Virtual Prepaid Mastercard® account

You can link your K Ring to a Virtual Prepaid Mastercard account; learn more here

What’s the K Wearables Virtual Prepaid Mastercard?

Your K Wearables Virtual Prepaid Mastercard funds the K Ring and the K Wearables Prepaid Mastercard, with each device drawing from the same pool of funds. You can connect multiple K Wearables devices to the same K Wearables Virtual Prepaid Mastercard.

The K Wearables Virtual Prepaid Mastercard is for use ONLY with contactless transactions via your K Ring.

The K Wearables Virtual Mastercard is a 16-digit long card number, an expiry date and a 3-digit security code, which is all you need to make a transaction online or over the phone. You can find your K Wearables Virtual Mastercard details in the “Devices” section when logged in to your K Account.

As with any payment card, you should keep the details of your K Wearables Virtual Prepaid Mastercard secure.

Funds, transactions and all K Wearables Virtual Prepaid Mastercard activity will always be displayed in your native currency by default.

What checks are performed when I sign up to the K Wearables Virtual Mastercard?

You will need to apply online for your virtual Mastercard, providing personal information including your name, home address and date of birth. We use this data to automatically verify your identity and address. In the event that we cannot automatically verify your identity and/or residency status, we will request proof from you and ask you to provide us with a photograph / scan of identity documents and/or a current utility bill which shows your address.

Please note that we can only accept documents containing the Latin alphabet.

The virtual Mastercard is a prepaid product, so we do not need to undertake a credit check when you register.

Are there any application restrictions?

Customers must meet age, residency and identification checks when applying for the K Wearables Prepaid Mastercard account to which K Ring is linked.

Customers must be 18 or over to register for the K Wearables Virtual Prepaid Mastercard.

You don’t have to be over 18 to buy a K Ring, but will need a valid debit or credit card, or PayPal account, to purchase it.

How do I link my K Ring to my account?

You’ll need to activate your K Ring before you can use it to make a payment. Until your ring is activated, it is not associated with your K Account and is completely inert.

Warning: once you active your ring this cannot be reversed.

To activate your ring you must first register for a K Wearables Virtual Prepaid Mastercard which can be completed in a matter of minutes by registering at mykring.com.

You may then link your K ring to your K Wearables Virtual Prepaid Mastercard by logging in to mykring.com and selecting Link Device from the Welcome Screen.

You will be asked to provide a Visual ID – this is the 9-digit code found in your ring's box.

Once your Visual ID has been entered, your ring is activated and you can add funds to your account.

Does my K Account have an Auto top-up facility?

Yes, it does! Auto top-up means you never have to worry about your account running low on funds, and your K Ring not being accepted in-store. If your funds fall below a pre-set threshold, Auto top-up will automatically add funds of a specified amount to your Virtual Prepaid Mastercard account.

Please note that Auto top-up takes place at 06:00 GMT each day, not at the precise time your funds fall below your pre-set threshold.

See how to use Auto top-up.

Are there any fees or charges to my account for using K Ring?

There are no fees for purchases with your K Ring.

You can load your K Wearables Virtual Mastercard with funds via bank transfer or a debit card without incurring fees.

Please see the detailed view of our Limits and Fees for using the K Wearables Prepaid Mastercard programme.

What is the End of Day Balance Adjustment?

The End of Day Balance Adjustment is an amount either deducted from or added to the balance of your Virtual Prepaid Mastercard (which stores the funds accessed by your K Wearables payment devices) to cover scenarios such as offline transactions (for example, a journey made on the TfL network) which are not always deducted from your balance in real time, and are therefore reconciled at the end of the day. This can also apply when a foreign exchange transaction is authorised, as it is deducted from your virtual Mastercard using the exchange rate at that moment (which may be different at the time of settlement) so is therefore reconciled via an End of Day Balance Adjustment.

Which type of account do I have?

There are currently two types of Virtual Prepaid Mastercard account, Lite and Standard, which have different limits and fees.

To see which account you have, first log in and go to “Account”.

At the top of the screen, click the arrow button next to your available balance to reveal more information about your account.


ABN AMRO customers can link K Ring directly to their bank accounts. For more information, please visit the ABN AMRO wearables Frequently Asked Questions.


Ordering K Ring

Find out more about how to get your K Ring, getting your size right and returns

In which countries is K Ring available?

The K Ring is currently available in the UK, but over the coming months we will be making it available across Europe and then to other countries around the world.

Do I have to be over 18 to buy a K Ring?

You don’t have to be over 18 to buy a K Ring, but will need a valid debit or credit card, or PayPal account, to purchase it.

You will need to be 18 or over to register for the K Wearables Virtual Prepaid Mastercard, to which the ring can be linked.

How do I determine my ring size?

We always recommend getting your finger measured professionally by a jeweller. However, if that’s not an option for you, please see our guide to ring sizing.

We also offer ring sizers in the K Store for taking your own measurement – but this will never be as accurate as a professional jeweller’s!

Which K Ring colours are available?

K Ring’s ceramic outer shell comes in black or white, and you can choose from 7 inner band colours: Ocean blue, Sun orange, Fire red, Leaf green, Candy pink, Jet black and Moon white.

You can see all the K Ring colour options in the K Store.

Can I have more than one K Ring?

Yes, you can attach up to 3 rings to your K Wearables Virtual Prepaid Mastercard, and they will all be sharing the funds... ideal if you want your ring to match your outfit!

You can turn off a ring that you are not using on the "Devices" page.


Can I buy a K Ring as a gift?

Yes, you can. The K Ring isn’t linked to a specific account until it’s activated, and it can be delivered to any UK address, so it’s perfect to send as a gift.

However, we recommend that rather than giving someone a K Ring, you instead give them a Gift Card; this way, the lucky recipient can choose their preferred edition and measure their own finger so they’re sure the size will be right. Gift Cards are available in the K Store, and come with a free ring sizer.

Please see our guide to ring sizing

Warning: once a K Ring has been activated and linked to an account, it CANNOT be reassigned to someone else!

Can I return my K Ring if it doesn’t fit?

Yes, you can. Please see our Purchase Policies page for more information.

Can I return my K Ring if I change my mind?

Yes, you can. Please see our Purchase Policies page for more information.

Can I cancel my order before my K Ring arrives?

Yes, you can. Please see our Purchase Policies page for more information.

What do I do if my K Ring doesn’t arrive?

Please email us at support@mykring.com with your order number and we’ll investigate.

What will appear on my statement after purchase?

When you make a purchase from our online store, your statement will show either:

Credit / Debit cards: 
K WEARABLES SHOP + 0844 502 0450

Payment to K Wearables Ltd

Kerv Wearables rebrand

We recently changed our name, so here we answer some of your questions about the rebrand

Why have you changed your name / rebranded?

We’ve changed our name because we reached the end of a trademark dispute with an undisclosed company with a “similar” name, the result of which meant we couldn’t complete the process of registering Kerv as a trademark.

Will I still be able to use my Kerv Ring?

The name change will have no impact on our service in any way, and you will be able to use Kerv Ring as usual, anywhere in the world that accepts Mastercard® contactless payments.

Has the ring design changed?

K Ring displays a new logo, but that's it – all its other unique design features and specifications are the same.

Can I exchange my Kerv Ring for one displaying the new brand logo?

Unfortunately, no. Your Kerv Ring is identical to the K Ring – apart from the logo – and will still be welcomed anywhere that accepts Mastercard® contactless payments.

What happens to the funds loaded onto my Virtual Prepaid Mastercard®?

Funds loaded onto your Kerv Virtual Prepaid Mastercard® will still be available to spend with your Kerv Ring, and with the forthcoming rings displaying the new logo.

Loading funds via bank transfer

If you used to load funds onto your Kerv prepaid Mastercard by bank transfer, then you can continue to use the same details to load your K Wearables prepaid Mastercard.

Login to your account and visit the Load Methods section for bank transfer details

Loading funds via debit or credit card

If you used to load funds onto your Kerv prepaid Mastercard by debit or credit card, then you can continue to do so with your your K Wearables prepaid Mastercard. Any cards you previously stored will be available in the Manage Cards section – just log in to your account and click Manage Cards

Loading funds via auto top-up

If you used the Auto top-up feature with your Kerv prepaid Mastercard then your previous settings will still be set up for your K Wearables prepaid Mastercard. If you wish to review or make changes, then simply log into your account and select Auto top-up

What impact will the name change have on me?

Impact on the customer experience will be minimal; the main differences are that there is a different email address for contacting support, and a different website address to log into your account, so you may need to update your bookmarks or saved contacts.

Who can I talk to about the name change?

If you have any questions about our name change, please get in touch with us at support@mykring.com