Compact USB rechargeable rear light that can be attached to aero seat posts, helmets and saddlebags. 2 Red LED Lithium Ion Rechargeable Batteries (DC3.7V/240mA) (Can be continuously charged without worrying about memory effect) USB Rechargeable, Charging Time: 2 hours, Low Battery Indicator: 3 hours, Up / Down Flashing: 3.5 hours, Flashing: 30 hours Rubber Strap Included Installation Diameter: Φ25.4~34.9 mm Aero Shape Seatpost Rubber for Round Seatpost Seat and bag clip included USB cable x 1. Waterproof performance: IPX6 L21 x W37 x H39 mm (light body) 0.6 oz (17 g). Product color may look different from the actual product depending on your display type and other specifications. 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. Please be aware of