Indeed, I was able to recharge my tablet Galaxy TAB 3 without difficulty during the drive and, meanwhile, the second USB port, I rechargeais my backup battery in OXA.
Unlike many USB dual that I tried, it is stable, without forcing plugs, switches off so easily: a delight to use. 5 Volts and 4.2 Amp it is not negligible, the load is therefore quickly.
In addition, the seller is very polite, sending very fast: a salesman to recommend.
Very effective, and at competitive prices, I advocate this double cigar lighter socket at OXA.