Casement Window C-R50 - 105x51 ( MULL)

This looks like the black piece off of a casement window hinge. These aren't sold separately, unfortunately. You'll need an all new hinge.

I believe you can use our 36-048 as a replacement. It own't be exactly the same as your original, but as long as you replace the top and bottom at the same time then you should be okay. The video below will go into more detail.