PDW Gravity Plus Tail Light. Features: Improved model with better battery life Designed with a brake light function, which uses an accelerometer to determine movement, the Gravity illuminates using 100 lumens to let others know you are stopping 2 modes (runtime): Solid - 20 lumens (12 hours), flash - 80 lumens (30 hours) USB rechargeable li-polymer battery Includes brackets for seatpost and seatstay mounting and Micro USB recharging cord Specifications: Brightness: 100 Lumens Battery Type: Rechargeable (Micro USB) Run Time: 10 - 25 Hours Beam Color: Red Color: Black Weight: 54g