TT Mystery

A blast from the not too distant past. I rediscovered it when I was looking for something else. I had used it when in hospital about 20 years ago with a broken leg.(That could be a red herring by the way). The back piece is a reflection of the front piece and an extra that may or may not help. Measures about 3x2 inches and this is the back of the whole thing.

See you tomorrow with the answer.