Hi there!
This reminds me of our 15-186 single coil balance clip which is often used with the 15-180 pivot shoe that's designed to use the Series 190 coil springs. Compare our dimensions with your old hardware to confirm this matches what you need.
If the 15-180 is what you have then the Series 190 would be the compatible coil springs. You'll want to check the band of the old spring for a stamped weight code. If there aren't any, you will have to weigh the window sash and divide the weight by the total number of springs in the window. These parts can be used on either side of the window.
I'm afraid this stamp doesn't match up with any of our spring weight options. With that said, you will have to weigh your sash on a scale to determine the correct weights.