Window balance / 25-5 BV CMC 1

Thanks for posting. I believe this might be either an S380-26 or S385-26 Channel Balance. The only difference between these two balances is the 'depth' of the bottom nylon shoe. See below. Measure your old balance's shoe depth to see what matches best. For a stamp option choose 2550.

Comparison of the S378, S380 and S385 balance shoes.