28C USB

Hello, thank you for posting,

With this combination of attachments, you could have either a 29" 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. If the shoe measures 7/8" instead, please let me know! 

The 28C stamp should translate to a 2830 stamp that can support a 16 to 23 lb window sash, but we recommend weighing the window sash to confirm.

Please review and let us know if you have any additional questions! 

Comparison of the S378, S380 and S385 balance shoes.