Size details :length: 4 cm / 1.57��light surface diameter: 2.5 cm / 0.98��tail lamp diameter: 2 cm / 0.78��Material: aluminum alloyLED: 6 white light， life 10000 hours， small power consumption， high brightness， light beam stabilitySwitch: switch to the tail push button (two block adjustment， 1= normally lights on 2= flashing)Save electricity， use 2 CR2032 button batteries. 360 + 135 + 360 �� to adjust lamp to freely.The bicycle light can be placed in the handles， can be put on front fork， back fork .Three kinds of modes: flash/steay/offPacking detail: 1pc lamp， 1 pc bracket， including 2 pc batteries