2640x27 Side Load Springs

Question

Have a large window with two side load springs with the only marking being 2640x27.on one of them. Evidently someone replaced one of them at some time because they are not exactly alike. I want to order a pair. What do i order. Photos attached

Paul · Accepted Answer

Your balance is showing some resemblance to our S390-27. Take a look and see if this looks correct to you. If so, go with the 2640 option.