Coil Balance Spring Weight Help

This looks like an older version of the Series 140 Coil Balance system. While in most cases we ask you to look for stamps on the coil springs themselves to determine the spring weight, with the Series 140 it's usually safe to go by the stamp on the assembly itself. The stamp of 7R indicates you need our S140-7, which supports 7 lbs of weight individually. Having one of these on each side of your window sash would support 14 lbs of weight total. Let me know if you have any other questions.