window balance id

Hi there

We just pulled these out of our window as we couldn't close it anymore. I, unfortunately, didn't take any photos of them IN the window.

The metal frame is almost exactly 28" long and the only markings I can find are "2740 BSI OF"

If you need any more info please let me know.

Thank you!

Richard

added additional photos

Hi

Thank you for the information!

Using my cheap digital caliper that measurement of the shoe is roughly 1.05" so I am assuming this is the 1" (however the shoe on my old balance is somewhat worn down or mangled - kind of hard to measure with only 1/8" being the difference between the two)

Also, the photos you posted show S351 and S390 but you reference S380-28 or S385-28.

2 new photos attached showing the caliper measurement and the "worn down" areas of the shoe - not sure if these were originally 1-1/8" and have worn down over their roughly 20 years of age or were originally 1" and got mangled making it measure ~1.05"

Can you please verify which ones I should order?

Thank you!