This bike tail light with adjustable lighting modes,is safe and perfect for outdoor riding use. Features: SMART BRAKE SENSING: The smart tail light will automatically enter into slow flashing mode during your braking time,and automatically turn off when you stopping for 10 seconds. HIGH BRIGHTNESS & Multi-MODEBike tail light offers 7 lighting modes,includes low,medium,high,slow flashing,medium flashing,fast flashing and breathing flashing mode. IPX6 WATER-RESISTANTMade of plastic material,endurable and water-resistant.NOTE: Please do not soak into water fro long time. USB RECHARGEABLEBuilt-in 500mAH battery recharges from your power bank,plug or any device with a USB port. EASY INSTALLATION:Saddle rail mounting bracket provided,quick to install or detatch on your bicycles. Specification: Mounting Position: Seat Post / Saddle Rail (optional) Color: Black / Pink / Multicolor (optional) Material: Plastic + Silicone Waterproof: IP X6 Battery: 1 * 3.7 v 500 mAh lithium ion battrey(included) Brightness: 100 Lumen Lighting Range: 180 Light Size: 44 * 34 mm / 1.7 * 1.3 in Light Weight: Approx. 56 g / 2.0 oz (with mounting bracket) Package Size: 110 * 80 * 35 mm / 4.3 * 3.1 * 1.4 in Package Weight: Approx. 80 g / 2.8 oz Package List: 1* Rear Light 1* USB Cable 1* Instruction 1* Mounting Bracket