Explanation: 2 times 500mhA are "obsolete" USB ports as standard for the PC, today's devices need virtually all !! least 1000MHA (1A / Ampeer) is even better as much power as possible! According to several statements that I have researched attracts each device only as much power as it needs! An iPad 2 as beispeill is today at something with !! 2100 !! thus MHA rich 500mhA or 1A only for the smallest consumers as USB fans or other toys