Coil Spring 1/2 in. Constant Force, 7.5 pound 1-1/4 Univers

Universal Constant Force balance for single or double hung sliding windows with 1.25 in. pocket

Pocket Width: 1.25 in. 
Coil Thickness: 1/2 in.
Weight Capacity: 7.5 pounds
Number on Balance is located on the end, sometimes hard to see

Available in several weight capacities: 3.5, 4.5, 5.5, 6.5, 7.5 and 9 pound. Coils can be mixed together to match appropriate sash weight
Sold as coil only. Can be combined with other parts to make balance - coils, support covers, brake shoes and pivots sold separately