Pella windows

Thanks for reaching out to us. Your pivot shoe appears to match our 15-199, which is designed to work with one of two different springs: either the 3/8" Series 165 or the 1/2" Series 160. 

Your next step should be to remove one of your existing springs so that you can measure it. That will allow you to determine which of the two available options are right for your window. You can also use that opportunity to make note of the weight rating, which is indicated by a stamp printed on the coil band itself.