Microsoft today revealed a new third-party accessory that should be of interest to Windows fans: The Token biometric ring will be Windows Hello-compatible and will allow users to sign-in to their Windows 10 PCs seamlessly.

“We’re thrilled to work with Token to make the Windows Hello experience even better,” Microsoft’s Chris Hallum says. “With its wearable design, Token logs you into Windows 10 seamlessly in a way that feels natural and familiar.”

The Token Ring, as its called—I will try to avoid joke about Tolkien’s Ring trilogy or the token ring technologies of the past—won’t ship until December 2017, and even then it will be US-only and will cost $250. But it does look interesting.

It’s made of sterling silver, and will come in 7 different sizes. (Token will send those who preorder the ring a sizer in advance.) It will come in brushed silver, black rhodium, or 14k rose gold finishes, the latter two of which will cost $50 extra.

More interesting is how it works: Before you put on the ring, you scan your fingerprint into a reader that’s built into the inside of the device, authenticating you. Then, Token can pass this authentication through to Windows Hello when you are near your PC. If you remove the ring, your credentials are locked in the device’s secure element.

Token isn’t just for Windows 10’s Hello feature—it will work with payment systems, smart door and car locks, transit cards, and in other scenarios. And it offers two weeks of battery life, which is a plus.

Looks interesting.

Tagged with Windows Hello