A crypto card lives a hard life. It rides in wallets and pockets, gets tapped against phones thousands of times, and is expected to keep working after years of that. So the materials are not a vanity decision — they are a reliability decision. The WATS NFC Metal Card is engineered to survive far more than a printed plastic card or a paper backup ever could, and this article explains the build: the steel and polycarbonate options, the durability ratings, the chip inside, and the one thing a tough body deliberately does not change.
The build: steel vs polycarbonate
The card ships in two materials that behave identically and differ only in feel. The brushed stainless-steel version weighs around 22 g and lands in the hand like a premium object — the heft is part of the point. The polycarbonate version comes in at around 5 g for people who would rather carry something barely-there. Both follow the standard CR-80 card format — 85.6 × 53.98 × 0.84 mm — so the card sits in a wallet slot like any bank card, and both run the same chip and the same tap behaviour. The choice is about weight and feel, not about how the authentication works.
Durability standards
Where the card earns its "metal" name is in what it can take. It is rated IP68, meaning it can sit submerged at 1.5 m for 30 minutes without water ingress — a spilled drink or an accidental wash cycle is not a death sentence. It is built to MIL-STD-810 tolerances across an operating range of -40 °C to +85 °C, so it behaves in a hot car or a freezing pocket. And it carries EMI and radiation shielding, which matters for a contactless device you want to read predictably and resist stray interference.
| Property | Specification |
|---|---|
| Materials | Brushed stainless steel (~22 g) or polycarbonate (~5 g) |
| Format | CR-80, 85.6 × 53.98 × 0.84 mm |
| Water resistance | IP68 — submersible 1.5 m / 30 min |
| Durability standard | MIL-STD-810, -40 °C to +85 °C |
| Shielding | EMI / radiation shielding |
| NFC chip | NTAG 216, NFC Forum Type 4 |
| Standard / frequency | ISO/IEC 14443, 13.56 MHz |
| Handshake encryption | AES-128 |
| Custom print | Optional UV print, 600 DPI, CMYK |
The chip inside
Embedded in that body is an NTAG 216 chip, an NFC Forum Type 4 tag. The contactless interface follows ISO/IEC 14443 and runs at 13.56 MHz — the same proximity-card frequency used by transit passes and contactless bank cards — and the handshake between card and phone is secured with AES-128. It is worth being precise about what this hardware is: a secured NFC tag, where the AES-128 protects the authentication exchange rather than guarding a signing key etched into silicon. We deliberately do not call it a certified secure element or tamper-proof key vault, because it is neither. It is an honest, well-built authentication tag.
What a tough build does not change
This is the part to keep straight. A premium metal shell makes the card durable; it does not make it key storage. The WATS card is a tap-to-authenticate companion: it authenticates access and adds a physical tap to sign, while your private keys stay in the non-custodial WATS apps. Metal protects the physical object and keeps the contactless read reliable; it does not turn the card into a cold wallet, and it never holds your coins. The durability is there so that the authentication factor you rely on keeps working for years — not so that you can entrust the card with your keys.
Build quality answers "will this still work after I drop it in a lake?" It does not answer "are my keys on it?" The answer to the second question is, and stays, no.
Personalization
Because the face is a clean metal or polycarbonate canvas, the card supports an optional UV print at 600 DPI in CMYK — a logo, artwork or a photo. It is purely cosmetic and changes nothing about the chip or the security, but it makes the card unmistakably yours.
Where to go next
For the full security model — how the chip, the non-custodial Hot Wallet and the card-loss scenario fit together — read WATS NFC Metal Card security, explained. For the broader question of whether a metal build is worth paying for, see are metal crypto wallets worth it?. And for the product overview and how to order, visit the WATS NFC Metal Card page.
Frequently asked questions
Why is the WATS card made of metal?
Durability. A card you tap thousands of times has to survive water, temperature swings and years of handling. The steel version is rated IP68 and built to MIL-STD-810 from -40°C to +85°C, with EMI shielding so it reads reliably. A polycarbonate version is offered for those who want something lighter.
Does the metal build mean the card stores my crypto?
No. The build protects the physical object and keeps the contactless read reliable, but the card is a tap-to-authenticate companion, not key storage. Your private keys stay in the non-custodial WATS apps; metal does not turn the card into a cold wallet.
What is the difference between the steel and polycarbonate cards?
Only weight and feel. Stainless steel is about 22 g and feels premium; polycarbonate is about 5 g and barely-there. Both use the same NTAG 216 chip, the same AES-128 handshake and the same CR-80 format, so they authenticate identically.