Window Balance Springs
Thanks for posting. See our S380-37 or S385-37 Channel Balances. The only difference between these two Series is the 'depth' of the bottom nylon shoe. With the Series 380 the depth of this nylon shoe is 1", whereas with the Series 385 it is 1-3/32". Compare with your own and see what is best.
Once you know what balance to pick, you must choose a stamp option. Your stamp option of 3630 is for a window sash in the weight range of 18 through 23 lbs.
The shoe is the other nylon attachment, the one that sits at the bottom of the channel balance when installed in the window. The depth is the measurement from the 'toe' to the 'butt' of the shoe, perpendicular to the bottom of the metal channel. See the picture below. In the nylon shoe of the Series 380, this measurement is 1". For the Series 385, it is 1-3/32".
