Highly waterproof & durable against vibration with long battery life and brake light feature Features: Built-in acceleration sensor to detect deceleration under braking Waterproof design (Waterproof performance: IPX7) Long battery life of up to 180 hours Rugged body with resistance to vibration while riding Achieves 360-degree light distribution High brightness, low power consumption design using 5 LEDs Equipped with 3 modes, 2 flashing modes + 1 constant mode Easy switching between constant and flashing with one button Mode memory function turns the light on in last used mode FlexTight™ (SP-11) bracket can be fast and securely fixed to the seatpost and seatstay without tools. Compatible with clip (C-2) to attach to pocket or bag 2x AAA batteries included Only 49g