Marking is 2730, length of channel is 28" long

Hi there!

With this combination of attachments, you could have either an S380-28 or S385-28 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 a spring strength option of 2730.

If you have any further questions just let us know! 

Comparison of the S378, S380 and S385 balance shoes.