Thanks for posting! This is a special kind of balance that will need to be custom made. Before we get started, I just need a bit more information.
First, I'd like you to confirm the length of the metal channel. It should be 25-5/8". As for the sash weight, it would be the weight of the window panel that slides up and down. These panels are known as sashes in the industry. A balance's function is to keep these panels raised when you open your window, so knowing its weight will let us calculate the best spring strength.
Finally, how many of these did you need?
