Balancer replacement

Hey there!

It looks like you have a tilt window. The 3/8" Series 900 or 9/16" Series 600 may be what you need. You must measure the diameter of the outer tube to determine the best match. It looks like the tube for this balance is cracked so you'll want to measure an undamaged version for an accurate measurement. 

You can re-use the pivot shoe if it's in good shape. If not, you can take a look at the 15-212's specifications to see if they match up with your old part.

Alternate image for 15-212