new balancers for vinyl window

Thank you for reaching out to us. We should be able to help with this but I'd like to confirm something before we get started. It appears you're showing two different stamped balances here. Can you confirm if they're from the same window or not? If they're from the same window, we will need you to get back to us with the precise sash weight. 

Thanks for confirming! After some research, we believe your balance system was made by Unique, USA which is no longer in business. What we suggest is using the Series 770 channel balance and 15-129 pivot shoe. It measures 1-1/4" wide, 9/16" thick, and 2-1/16" tall though the height doesn't matter too much. 

The metal channel should measure 30" long and you may need the 30C stamp option for the 29C balance and the 30D option for the 29D balance. A pair of balances with the 30C stamp will support a sash weighing 19 to 24 pounds, and a pair of balances with the 30D stamp will support a sash weighing 24 to 29 pounds. You can always weigh each sash to confirm they fall within these ranges.