This is a plate with the Haskell sign designed to be worn on the body.
If you don't know the programming language Haskell you can take a look here:
It's slightly arced shape makes it optimal as the mainpiece of a headband or a wristband.
It's size is roughly 38x18mm.
The holes are 3mm in diameter so that a leather strap can be feed through.
There is also a version with slits instead of holes aviable on my shop.