Window balance part (shoe)???

I'm not sure what your question is. Are you asking for us to identify the pivot shoe? One shoe can usually work for both the left and right side, so they are very rarely differentiated.

If you need a new shoe, it's hard for us to identify what you have based on this picture. You do not show the whole shoe, and I do not know its dimensions. That said, I've made a list of possible replacements for you which you can view on the right side of this page. Carefully compare their style and dimensions to your own hardware to confirm a match.