At first glance this looked like a few keys that had broken off a board or the last bite of a Hershey's dark chocolate bar. And we undoubtedly would have had more use for the latter than its actual purpose.
The "Ring Mouse" is an odd peripheral that's designed to be worn on a finger, with a tiny trackball controlled by your thumb. We really wish a video had been included with the product literature, because it sounds as if only a contortionist could operate it as described. And it's corded, as Boing Boing notes, making it a deal-breaker for us even if we were double-jointed.
We'd suggest something more ergonomic like the "" if you're looking for a different way to navigate. Unless you perform in a carnival.