Feature Use 4pcs high quality LED Bicycle rear light, super bright bike rear rack light. With 2 modes,one is steady,one is flash. Use 2pcs AAA batteries,easy to replace.(Battery not included) Up to 60-80 hours Including bike reflector,improve safety. tool-le installation on the bicycle carrier, 100 meter visibility, Distance between 2 screws: Adjustable,from 50mm to 70mm is ok. Enjoy safety in rain, snow even thunderstorm extreme weather Advantages 1: Screws are removable,can fits for most kind bike carriers. Advantages 2: Bicycle rear light use 4pcs high quality led,very good for use as bike rack warning light. Advantages 3: This bicycle rear light use 2pcs AAA batteries to work ,easy to replace.Working time up to 60-80 hours. Advantages 4: Including one bicycle rear light and one bike reflector.Even your battery have no power,can ensure use it as bike warning light. Package include: 1.Shelf installation1*Bicycle rear light2*Screws2.Seat tube installation1*Bicycle rear light2*Fasten the lamp holderWarning:The batteries are not included