Specifications: Working: Approx. 36 hours Power: 2 * AAA batteries (not included) Size: 70 x 80mm/2.7 x 3.2"Material: PVC Package Included: 1 x Bicycle Laser Beam Rear Tail Light Lamp 1 x Bicycle Mount Note: Please note that slight color difference should be acceptable due to the light and screen. There is 2-3% difference according to manual measurement. Please check the measurement chart carefully before you buy the item. (1 inch = 2.54 cm) Ordinary light, Quick flash, Slow flash, Changeable from right to left, Changeable from left to right, Circular explosion, Circular slow flash. Remind someone else of keeping distance, add safety. This little laser beam tail light will ensure your safety while riding in the darkness. Waterproof, safer in water fog when riding in the rain Use for jogging, walking, bicycles, car emergency, horse-riding, road emergency camping, ETC.