LightRail 5.0 Trolley Wheel Replacement: This DIY light mover kit consists of all the white wheels. So, the LightRail 5.0 Trolley Wheel replacement includes the Outer Trolley Wheels (4 count). And, it includes the Inner Drive Trolley Wheels (2 count). And, these are available for purchase for anyone who wants to do this replacement themselves. Note: The newer design for LightRail 5.0 Motors only have the four Outer Trolley Wheels to replace. In that case, use the four like-wheels as your four trolley wheels to replace. See specific indoor grow systems product details farther below.