To activate your White LED Headlamp, press the button on side of the light. With each button push, choose from steady lighting, extra-bright steady lighting, and eye-catching blink for safety. To wear, adjust the comfortable elastic strap to fit your forehead or helmet, and you’re ready to roll. Head Light Dimensions (W x H): 3″ x 1.25″ Strap: One size fits all. LED Colors: White Comes ready to use with 3 replaceable AAA Batteries.