Casey from SWISCO responded:
May 29, 2020
Hello, With this combination of attachments, you could have either an S380-34 or S385-34 channel balance. You need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment. The stamp on the back of your metal channel should tell you what spring strength option you need, but you can also look at the chart under the product description and choose the option that will support a 40-pound sash. Thank you and let us know if you have any other questions or concerns. Comparison of the S380 and S385 balance shoes.
|