The DEWALT DCB090 12V/20V MAX USB Power Source is durable enough to withstand jobsite abuse. Able to charge up to 2 small USB compatible electronic devices on/at the jobsite off your 12V or 20V MAX Batteries when AC power is not available. This unit allows you to work with all DEWALT Slide Style battery packs. It has an indicator that tells you when unit is powered on and ready to charge devices. And, similar to a fuel gauge, it indicates the amount of power remaining in the battery. Commonly used for: charging mobile phones, charging digital audio devises/MP3 players, charging digital cameras, and charging small electronic devices when power is not available.