2 LED/1 LED based with transparent cover cap. Very bright LED is required. Bungee cord/elastic strap for mounting on bike or to keychain. Bottom side with rubber cavity for better grip on handlebar. Blinking function and constant light (without holding!). 1 LED is interesting only if plastic cover cap is attached and in mouse style shape Features: The light is unique and beautisul,it has two mode of switch ,one is long bright,the other is flash. can be fixed to handlebar and seat handle as a taillight,which is very convenience.Also,it can be fixed on the helm or as a keyhole,very dedicate and used extensively. Adopt CR1220 button batteries.