The product image does not match the description of the adapter. The text promises a full-bodied power output of 2x 2100mA during 1x and 1x 2100mA 1000mA is on the adapter. Why the manufacturer should make worse information than the adapter really makes?
I've tried it with iPad2 and iPhone4. Both units are loaded - no matter to which port
Let's see what the manufacturer says.
The plastic housing looks a bit cheap, but it disappears so in the charging socket of the cigarette lighter.
For my purposes, the unit is ok.
Addendum: After some testing, I've found that the adapter is not interference suppressed. The radio reception in the car is extremely disturbed.
My recommendation: Do not buy - scrap