Window balances

Thanks for posting. This looks like an older version of the 15-177 Pivot Shoe, which uses Series 152 Coil Balance springs. For a 16.6 pound sash, use two of the S152-8 8 pound springs, one on each side of the sash. This will give you 16 pounds of total support, close enough to the exact sash weight. If your old coil covers are undamaged, you can reuse them. Otherwise see the 15-143, 15-144 and 15-145. These parts sandwich around each coil. Let me know if you have further questions.