Now the outstanding OttLite 13W portable desk lamp is available with a rechargeable battery that allows you to use this lamp indoors, outdoors, and even in transit. It comes with an AC adapter which is used to power the lamp and recharge the battery. Once charged, the battery provides 2.5 to 3 hours of use. The 13 watt fluorescent OttLite bulb is rated to last 10,000 hours. It measures 11" high when closed.