WW Milgard Balance Springs replacment

Hello there. This looks like either an S380-12 or S385-12 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best. For a stamp option choose 1120.

Comparison of the S378, S380 and S385 balance shoes.