Balance Sliders

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!