With Sydnee at your desk, you can recharge up to 4 smartphones, tablets, e-readers or MP3 simultaneously. Each individual USB port pumps out 2.1 Amps/10W of power for quick charging. Sydnees smart charge feature detects which device is charging and adjusts to provide optimum supply of power. There is also built in short circuit protection to provide you with peace of mind while your devices are charging. Li-Ion (included) .