EPI Windows

Thanks for posting. I believe this is either an S380-20 or S385-20 Channel Balance. The only difference between these two balances is the 'depth' of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below for reference. Measure your old balance's shoe depth to see what matches best.

Comparison of the S378, S380 and S385 balance shoes.

You then have to choose a stamp option, which reflects the strength of the balance. Your old balance's stamp of 19-9 is from an outdated rating system. That second number, '19', likely reflects the weight of the window balance--19 pounds. If that's the case, then you can choose 1950, which denotes a balance that will support a window in the weight range of 18 through 21 pounds. You can always weigh the window sash to confirm this. Let me know if you have further questions.