Tilt double hung wind rated aluminum window, looking for spiral balance springs

Question

I do not know the manufacturer of the windows. Included is information from a window, not the one needing springs, to help identify the window if needed, 3B740 Ord: 18257237.4, 744F140, 3060EQ, WH, FIN, 5/8 FLAT, 9/9, INS, SSB... I have several windows in need of replacement springs, I believe a series 900 will do the job,
The tube is plastic construction, .420" and 28" in length. Please confirm a spiral balance spring that will do the job.

Tom · Accepted Answer

Hello! As long as the diameter of the outer tube is 3/8", and its length is 28", then I agree that our S900-28 is your best option. You'll also want to weigh your sash on a scale to determine the correct color option. The White Tip you have on yours may not be the same as modern White Tips. Back in the day, White indicated heavier sashes, but now it indicates light sashes. It's better to check and refer to the chart on our S900-28 store page to be sure.