Commuter x4 lighting system for extra visibility the x4 lighting system is a great choice for commuters the light offers extra visibility from more angles than a standard seatpost mounted light making you stand out more on busy roads 4 led fibre optics usb rechargeable adjusts to backpacks up to 35 litres water resistant multiple flash and fade settings multiple output options for power saving allows access to all zips and pockets whilst in place can be worn over shoulders without a backpack