Each slider is stamped with either 2390T-B.S.I.-25 or 2390T-B.S.I.-26. The metal housing is 24 in. long, 9/16 in. wide, 5/8 in. deep. The lower pulley end has a winged shoe, the top has no wings and tapers at a 45* angle.
I am thinking these may be 24" Series 350 sliders, but would like to confirm.
Thank you!
Tom from SWISCO responded:
July 10, 2018
Without a doubt. S350-24. Weigh your window sash to choose one of those "options" from the chart on the product webpage.