Identify parts

To start, how long is the metal channel by itself? I can't tell where your measurement begins. It looks like 24" from metal to metal, but please confirm that!

Then, I need the weight of the window sash. It's inconvenient, but necessary to calibrate the balance. Remove the sliding part of the window and weigh it.

Finally, which of the two bottom attachments in my photo do you have? Do you have a 1" depth, or a 1-1/8" depth? All this information together will allow me to identify the balance. As I said, it's a little inconvenient, but I do need all of it.

Comparison of 15-001 & 15-002