The Simson Battery LED set "Simmy" has an silicone body and universal silicone straps for ease mounting on the the seat post or handlebar. The lights have an on, off and flash function. The LEDs provide a bright light output up to 29 LUX at the headlight, and 13.5 LUX at the taillight! The button is easy to operate even with gloves or wet hands. Includes 4 x CR2032 batteries.