The S400-27 for Wood Windows?

Thanks for writing in. Earlier mill-work companies that made wood sash windows used our 5/8" Non-Tilt Spiral balance, the Series 500.

Yep, those are for our Series 400. That's only 3/8" in diameter though, and we don't recommend a skinny balance like that for wood windows. They tend to be pretty heavy and the Series 400 often struggles to hold up the weight. For the Series 500, we recommend a bracket like our 17-012.