Sash balance bath room window.

Hello, Robert.

My recommendation is the Series 380 or Series 385 based on what I see here. The best match will come down to the bottom shoe, specifically the depth of it. You'll have to measure as shown in the image below to determine the accordant Series. 

I'm afraid I can't make out the faded stamp so you may want to check the balance on the other side of the window for a clearer one. Those numbers will indicate what strength option you'll need to select for your replacements.

Comparison of the S380 and S385 balance shoes.

Great! In that case, you'll want the S385-13 with the 1220 strength option.