CAETLE&reg; Anodised Aluminium Rear Derailleur Jockey Wheel Pulley Shimano SRAM 11T A5 Black ULTRA BRIGHT LASER TAIL LIGHTS: 5 LED Lamp with 260 degree wider visibility and 2 laser creates a lane around your bike, helping to protect and keep you safe ALWAYS BRIGHT: Flash, slow flash, left to right, right to left and left to right slow flash, flash, flash back and forth Light, Flashing modes changing by pushing the LED button, satisfied your needs in different situation. EASY INSTALL IN UNDER 5 SECONDS: Can suit for the seat post 20 -36mm. IPX-2 Water resistant rated protected against, tilt 15 degrees Anti-rainwater. (Not dive!) POWER BY: 2 AAA batteries (Not included), this laser tail light works for up to 36 hours, no need to worry about lack of power with a spear battery.