The bike light is made of silicone shell and two 2032 batteries. Contains 3 flashing modes: full light, fast flashing and slow flashing, so you can be easily seen in early morning fog, dusk, nighttime, and dawn. It is waterproof and has no peculiar smell, not easy to break. High visibility make you safety for night cycling, walking dog, running, jogging, fishing, camping and other outdoor activities. 1 37/64" L x 1 3/16" W x 1 3/16" H