Window balance ? Pegs in window go onto them and allow them to go up and down and stay open.

Thanks for posting. This is a coil balance system. This is the 15-177 Pivot Shoe, which works with Series 152 Coil Balance springs sold separately. See the videos below for guidance on how to remove and replace these systems, and also how to choose spring weights for the coil spring replacements. Let me know if you have further questions.