Window balance parts inside window

Thanks for writing in! The plastic piece you have pictured here looks like it could our 26-399 Pivot Bar Housing for upper sashes. This is typically used with our 26-400 Top Sash Pivot Bar. 

To confirm that this is the correct replacement, carefully look over the dimensions and compare them to your existing pivot bar to determine if this is the replacement you'll need. See what you think.

Measurements for 26-399

profile view of 26-399