3 1/2" wide 72" long

The 23-242 is for convex rollers, or wheels that have a rounded edge. Your track might be for concave rollers, or rather it has rails for wheels that have a groove around their perimeter to run on. if so a track like our 23-272 would be better for you. Look over the end profile dimensions to confirm. If the 23-272 is what you need, you can return the 23-242 via our Return Policy. See here.