The Light Rail 5 Fore & Aft Crossbar Mounting kit allows the user to mount their crossbar and hang their lights in line with the rail. The Add-A-Bar kit includes Light Rail 5 trolley, crossbar, 4 foot push rod and all the hardware needed. Does not include 4’ rail. The Light Rail 5 Add-A-Bar kit allows for an additional (3) light maximum expansion to existing Light Rail 5 complete systems. Add-A-Bar kits may need an additional 4' Auxiliary rail (710147) for systems that demand more than 2 total crossbar setups. The Light Rail 5 Add A Bar Kit Contains: Adjustable Crossbar (81â€, 87â€, 93â€) Light Rail 5 Auxiliary Trolley Sectioned Push-Pull Rod Mounting Hardware Instructions