Trolley Wheel Replacement Kit for LightRail 3.0, 3.5 and 4.0. This is great for DIY customers. Installation is super simple, and there is even a tutorial video about it on YouTube (URL: https://www.youtube.com/watch?v=MIbtIWyNFp0). The Trolley Wheel Kit comes packaged with 4 new trolley wheels and screws in a header labeled zip lock.