Rectangular Ballasts wit a cord.

Question

These are 22 inches long and have the number 21527 stamped on them. It could possibly be 21S27 hard to say.
I have done a bunch of spiral replacements but never these style.

Casey · Accepted Answer

Hello,

We can't be sure with the hardware still installed, but the 15-178 or 15-188 pivot shoes would be a good place to start. Review the specifications below to determine if one of them matches your part.

Dimensions for 15-178

Alternate image for 15-188

The channel balance resembles the S770-22, but your stamp code is a bit unusual. We'll need to know the exact weight of the window sash the balances support ot determine the strength option needed for your replacements. Thank you!

Close up view of the Series 770 balance top.

Close up view of the Series 770 balance bottom.