Tiny Tuesday - What's It?

Recently added to my camera collection and this wee (tin film canister included for perspective) bit of gear was included in the kit. I would image a few of you will know that it isn't a 1950s spy camera (my first guess) and may have used one. The answer will come tomorrow and yes, there will be a quiz on Friday but no worries - it will be open book.

The extra may provide a bit of a clue - good luck ... and the adventure through the viewfinder continues,