The Cateye Reflex Rack Rear Bike Light is compatible with any type of rear rack and functions as a battery tail lamp with a reflector for rear rack mounting. It meets various lamp standards including StVZO, RKF, and Danish, and reflector standards such as StVZO Z, BS, UN IVA, UN IA, and CPSC. The light allows for tool-free battery exchange and weighs 106g. It is powered by 2 AA alkaline batteries.