This model is a Buck Off key ring / key chain!
This keyring is 5cm wide, 5.5cm tall and is 6mm thick.
Keychains are designed with a 'channel' to allow for a 2.4mm (or smaller) ball chain to be looped through. Ball chain is available very cheap online in a variety of colours - we suggest cutting the ball chain to a length of approximately 15cm.
To print the back of the two sided version perfectly, colour it in your slicer and set the height on the bed 0.2mm lower than default.