To activate your Red Bike Light with Ground Illuminating Lasers, press the LED button atop the tail light to activate 1 of 7 light modes, from steady to 6 different forms of flashing. Press the LASER button atop the tail light to activate 1 of 2 laser functions: steady and flashing. LED/Laser Colors: Red Dimensions (L x W x H): 5" x 2.75" x 1" Red Bike Light with Ground Illuminating Lasers comes ready to use with 2 replaceable AAA Batteries.