Gravity Plus USB Tail Light

The Gravity Plus Tail Light has a built-in accelerometer that detects deceleration or swerving and automatically changes to a super bright, solid beam to warn following traffic. To allow the accelerometer to calibrate, always install the Gravity+ on your bike before powering it on. Hold the power button down for 1 second to turn the light on or off. Then, keep your bike still for 1 second after pressing the power button to complete the calibration.  Specifications Automatic accelerometer brake light function shines 100 lumens bright 2 Modes (runtime): Solid - 20 lumens (12 hours), Flash - 80 lumens (30 hours) USB rechargeable li-polymer battery Weatherproof exterior for all season riding Seatpost and backpack clip mounts included Mounts vertically or horizontally Includes USB-C recharging cord Weight: 1.9 oz