The Simson Battery LED set "Bullet" has a very sturdy, lightweight aluminum body. The universal rubber mounting straps are easy to mount on the seat post or handlebar. The lights have an on, off and flash function. The LEDs provide a light output of 2.5 LUX at the front light, and 1.5 LUX at the rear light. The button is easy to operate even with gloves or wet hands. This makes it the ideal set for the sporty cyclist! The rubber mounting band is usable up to 35mm width. Includes 4 x CR2032 batteries.