This waterproof flashlight has a environmental protection design. Never need the battery. Aslo there is a high-luminance LED light, no need of replacement. It can give out light for 3 to 5 minutes after shaking for 30 seconds and will flash continuously if you stick to shaking. High sealed, all-weather waterproof forever. Colors available: Transparent, transparent-blue, transparent-red, transparent-green, and etc. Product specification: L =17CM (Small) L = 24CM (Midium) L= 28CM (Large) Notes: The above size means the length of product