A crypto card is built in metal for durability rather than for storage: the body has to survive years of pocket wear, water and temperature swings, while the keys live somewhere else. The WATS NFC Metal Card is a CR-80 card in 316L brushed stainless steel or ultra-light polycarbonate, rated IP68 and built to MIL-STD-810 across -40 °C to +85 °C. Inside sits an NTAG 216 chip whose contactless handshake runs over ISO/IEC 14443 at 13.56 MHz and is secured with AES-128. What the tough build deliberately does not change is what the card holds: the WATS card stores no private keys at all. It is a tap-to-authenticate companion, with a unique card ID paired to exactly one device, for keys that stay inside the non-custodial WATS apps.
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 styling 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: 316L steel vs polycarbonate
The card ships in two materials that behave identically and differ only in feel. The 316L 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. Those ratings are worth understanding literally rather than as marketing adjectives: IP68 describes ingress protection, MIL-STD-810 describes an environmental test methodology, and neither says anything at all about cryptography.
| Property | Specification |
|---|---|
| Materials | 316L 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 |
| Memory | 256 bytes |
| Handshake encryption | AES-128 |
| Custom print | Optional UV print, 600 DPI, CMYK |
| Private keys stored on card | None — keys stay in the WATS apps |
The chip inside
Embedded in that body is an NTAG 216 chip, an NFC Forum Type 4 tag with 256 bytes of memory. 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. WATS deliberately does not call it a certified secure element or a tamper-proof key vault, because it is neither. It is an honest, well-built authentication tag. And the reason it cannot be a wallet is capability rather than capacity: a private key is only 32 bytes and would fit in that memory several times over, but the card is built to carry an identifier and answer an authentication challenge — it does not derive keys, hold a recovery phrase, or compute the signature a transaction needs. That work happens in the WATS app, on your device.
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 NFC Metal Card is a tap-to-authenticate companion: it authenticates access to your WATS wallet and adds a physical approval step, while the signature itself is produced by the WATS app using private keys that never leave your own device. WATS is fully non-custodial and never holds a key. Each card carries a unique card ID and pairs to exactly one device, so a card someone else picks up is inert metal in their hand. In practice that makes it closer to a physical security key than to a cold-storage vault, and the durability exists 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, the pairing or the security model, but it makes the card unmistakably yours.
Where to go next
For the full security model — how the chip, the non-custodial WATS apps 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?.
The practical takeaway: if you want a card that treats metal as engineering rather than decoration, the WATS NFC Metal Card is the concrete example to start from. The first time you tap it in the WATS Mobile App it pairs to exactly one device, and it sits alongside the rest of the non-custodial WATS line — the Chrome Extension, the Mobile App and the Hot Wallet — across Ethereum, Arbitrum, Optimism, Base, Polygon, BNB Chain, Solana and TON. Because the card authenticates rather than signs, the same tap works the same way on every one of those chains. Specifications, materials and ordering are on the WATS NFC Metal Card page.
Frequently asked questions
Why is the WATS NFC Metal Card made of metal?
WATS builds the card in metal for durability, not for storage. A card you tap thousands of times has to survive water, temperature swings and years of handling, so the 316L stainless-steel version is rated IP68 (submersible 1.5 m for 30 minutes) and built to MIL-STD-810 from -40°C to +85°C, with EMI and radiation shielding so it reads reliably. A polycarbonate version is offered for people who want something lighter.
Does the metal build mean the card stores my crypto?
No. The WATS NFC Metal Card stores no private keys at all. The build protects the physical object and keeps the contactless read reliable, but the card is a tap-to-authenticate companion: your private keys stay in the non-custodial WATS apps, WATS never holds a key, and metal does not turn the card into a cold wallet. It is closer to a physical security key than to a cold-storage vault.
What is the difference between the steel and polycarbonate WATS cards?
Only weight and feel. The 316L stainless-steel card is about 22 g and feels premium; the polycarbonate card 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 (85.6 × 53.98 × 0.84 mm), so they authenticate identically.
What chip is inside the WATS NFC Metal Card?
An embedded NTAG 216, an NFC Forum Type 4 tag with 256 bytes of memory. Its contactless interface follows ISO/IEC 14443 at 13.56 MHz and the handshake with your phone is secured with AES-128. WATS describes it accurately as a secured NFC tag rather than a certified secure element: the encryption protects the authentication exchange, and no signing key is stored on the card.