Good waterproof effect-The bicycle tail light is made of high quality plastic material, very waterproof. The rear lights can withstand all bad weather conditions and riding in the rain is safe and worry-free. It also has a low battery reminder function. .6 Flashing Modes-The bicycle taillight has 6 dimming modes, which provide extremely bright illumination of the 220 side of the rear, which is easier to find and greatly improves safety. .Proper Size - The proper seatpost size for bicycle taillights is: 25-27mm / 0.98-1.06inch. Use a screwdriver to quickly complete the installation and disassembly, simple and convenient. The taillights can be firmly fixed on the frame without worrying about loosening while driving. .Battery Powered-The bicycle taillight can be powered by 2 AAA batteries, waterproof and shockproof, especially suitable for cross-country bicycles and friends who often ride at night. (Note that this model does not contain batteries, batteries need to be purchased separately).Multi-Function-Bicycle taillights can be used not only on bicycles, but also on helmets, strollers, backpacks and pet collars. Outdoors, it can be put on the backpack, mounted on the shelf, on the arm and other security warning places, the effect is very ideal. .