The Heads have Two High Intensity LED Bulbs with Three postions, OFF, 1 ON, 2 ON, 3 ON or All Four Lights ON. Has two flexible adjustable supports. Uses AAA batteries, USB Computer Port or Use the 110V Transformer and USB Connecting Wire Included. LED Bulbs use very little power to get a lot of light so it will last an amazingly long time if you decide to use AAA batteries.