Drive Wheel Replacement Kit for LightRail 3.0, 3.5 and 4.0. This is great for DIY customers. The Drive Wheel Kit comes packaged with a new tension spring and fasteners in a header labeled zip lock with instructions. Drive Wheel O-Ring Kit (Tension Spring, O-Ring, Nut, Bolt). Includes a black rubber wheel, tension spring and one bolt. For an instructional video demonstrating the assembly, go to https://www.youtube.com/watch?v=_NBIV-IjSi8

Light Rail 3.5 is rated to 35 lbs
Light Rail 5.0 is rated to 100 lbs