Parts for single hung window installed in 2007
Hello there. This looks like the 15-180 Pivot Shoe, which works with Series 190 Coil Balance springs. For new housing, see the 15-186 Clip and 15-182 Bushing. Let me know if you have further questions about any of this hardware.
If your old coils have no stamps to use as a reference, then you'll need to weigh your sash on a scale. Any bathroom scale will do fine.
Once you have the weight, divide that by how many springs support the sash in total. In your case that appears to be two.
So for example, if your sash was 10 pounds then you want the 5 pound option (S190-540). If it's 8 pounds, you want the 4 pound option (S190-440). And so on.
For the S190 stamps, the weight is represented by the first digit.