Input Amperage for Nexus 7

view story

http://forums.androidcentral.com – I have just purchased a New Trent IMP120D for on-the-go charging my Nexus 7 when away from mains electricity. There are two outputs: 5V @ 1A and 5V @ 2.1A - which would be the right one to use for the Nexus 7? On the same theme, using a suitable cable is it OK to charge directly from a car's phone / cigarette socket? (HowTos)