This Wheel Light is suitable for cycle hub with diameter from 19mm to 36mm. There are 3 shining modes, fast flashing, low flashing and steady shining. The waterproof level is up to IP55, so you don't need to worry that it will be damaged by the rain. A nice decoration for your bike. Features - Light Color: Blue. - Material: Plastics. - Size: Approx. 9.5 * 9.5 * 1.7cm/ 3.7 * 3.7 * 0.7 inch (L*W*H). - Installing Calibre: 19 - 36 mm. - Waterproof: IP55. - Battery: Three LR44 batteries(Included). - Endurance Time: about 12 hours. - 3 shining modes: Fast flashing, low flashing and steady on. - Does not affect the center of gravity and its appearance. - Can be also used in kid's bike. - No requirement, will still light when the bike stops. - Bright lights, suitable for night riding and as a warning light. - Awesome for cycling, riding, creative sports LED light.