part for window
Thanks for posting! This cover is part of a coil balance assembly. The springs appear to be disconnected from the shoe, so there's a possibility you'll need to replace this as well. It is likely still attached to the bottom of the window sash.
If you would like to replace it, I'll need to see a clear photo of it to identify the correct match.
The balance support you have here appears to be either the 15-205 triple support or the 15-206 quad support. These are compatible with the 3/8" Series 165 Coil Balance. Be sure to double check the width of the coil to confirm this is the right series.
You'll need to look for a stamp/marking on the coils to determine the correct springs for your assembly. There is a video tutorial below with instructions on selecting the coils.
Please let me know if you have any questions.