Compact USB rechargeable front light with 100 lumens brightness. Luminous Flux: 100Lumens Luminous Intensity: 480cd Illumination: 4.5Lux/10M 3W White LED 1 Li-ion Rechargeable Battery Built-in (DC5V/2A) (Can be charged without worrying about memory effect) USB Charging Time: 2 hours Battery Capacity Indicator Low Battery Indicator Illumination : 4 hours Flashing High Brightness : 1 hour : 20 Time, Dayflash: 8 hours Waterproof Performance: IPX4 handlebar bracket, Mountable diameter: Φ 0.7 - 1.3 inches (19 - 32 mm) USB cable, 2 cable ties, Velcro strap included for helmets, L2.0 x W1.1 x H0.8 inches (50 x 28 x 21.6 mm) (19 mm); The color of the actual product may look different depending on the type of display. Product specifications, logo design, etc. may be subject to change for product improvement. We also cannot answer measurements or personal fit that the manufacturer does not announce.