I think these are called coil balances they work but the cams are disintegrating and the sash pivots are breaking also when trying to remove the sash
Bob from SWISCO responded:
October 11, 2019
Thanks for posting. This looks like our 15-177 Pivot Shoe. This shoe is compatible with our Series 152 Coil Balances. For a new pivot bar, see our 26-030.