Window Balance 26 5 CX CMC 7

This looks like a Series 385 channel balance, which you can verify by measuring your bottom balance shoe. If your balance is 27" long, and your balance shoe matches the one in the photo below, then you can go for the S385-27 balance. Your stamped code suggests you may need a 2650 stamp option, but you can weigh your window sash to be sure. Each balance has a chart in the product description that tells you which option to choose, based on your sash weight.

Alternate view of 15-004