A home owner from Colorado says:
April 19, 2016
I need some replacement Sashes for vinyl windows. The stamp on the bar says 25 3 ok, and also B.S.I. When I measured the bar it was closer to 26". Which do I go with? How do I know the spring weight? I do not know the manufacture of the windows as there is no markings at all. Thanks
Tom from SWISCO responded:
April 21, 2016
Thanks for posting. Sounds like you have a 26" block & tackle balance with a stamp option of 2530. I'm afraid that's all I can tell based on your information, though. Now you just need to pick out the top and bottom fittings in order to determine the Series.
I recommend that you look at our Channel Balance Home Page and follow the steps in order to find the Series that best matches what you have.