This Cateye Tight Kinetic Rear Cycle Light is designed for safety and convenience. It features a built-in acceleration sensor to detect braking deceleration and is waterproof with an IPX7 rating. Enjoy long battery life of up to 180 hours and a rugged body resistant to vibration. The light offers 360-degree light distribution with 5 high-brightness, low-power LEDs. Choose from 3 modes: 2 flashing and 1 constant, with easy one-button switching and a mode memory function. The FlexTightâ„¢ (SP-11) bracket allows for tool-free attachment to seatposts and seatstays. It's also compatible with a clip (C-2) for bags or pockets. Two AAA batteries are included, and the light weighs only 49g.