Window balance

These balances appear to be either the S380-24 and S380-30, or the S385-24 and S385-30, respectively. The only difference between these two balance Series is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the image below for reference, and compare both with your old hardware to determine what you need. Let me know if you have further questions. 

Comparison of the S380 and S385 balance shoes.