Alcoa vinyl tilt windows

Thanks for contacting us. It sounds like you need a 5/8" diameter Series 600 spiral balance. As for the length, you might be okay going with 34", but it's hard to tell. Are you making sure to only measure the outer tube? It looks like your outer tube is missing, perhaps broken off. See if the other identical windows still have their tubes that you can use as a reference.

As for the color tip, black might be a bit much for a 15 pound sash. Using the S600-34 as an example, two balances with a black tip can carry sashes weighing  31 through 40 pounds. That's WAY too strong for a 15 pound sash. You may want to get the exact weight to be sure. We have a chart on all our Series 600 store pages that tells you how much weight each color option can support.

The measurements actually are listed on the 15-173 webpage, but I'll post them here, too.

Dimensions for 15-173