I never used them but I can tell you this...remember when ya buy one you need a compressor thats not loud as hell like most, an air dryer, and any air tool I've ever seen or used needs to be oiled daily or they wear out FAST... I for one don't want to be tattooed by something thats spraying left over air tool oil or water all over my fresh tattoo..............
Of course I'm biased to the electric tattoo machine