seeking replacement balance spring sets

Hello,

With this combination of attachments, you could have either an S380 or S385 channel balance. You’ll need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment. You'll also need to locate the stamp code on your metal channel to choose the corresponding strength option for your new balances. 

Thank you and let us know if you have any other questions or concerns.

Comparison of the S378, S380 and S385 balance shoes.

Based on your stamp, which may be from an outdated weight system, I would recommend weighing your window sash and following the chart under the S380-20 product page. The 3 at the end may indicate that you have a 30-pound sash, but the only way to confirm would be to check the weight. Please get back to us with your sash weight and we can go from there. Thank you!

Great, see our S380-20 with a 1960 strength option for a sash weighing between 22 and 26 lbs. Thank you!