Well I never got welts from Nutropin Depot, Nutropin AQ, Jintropin, or Humatrope, all 191aa. If it's not exactly like your bodies 191aa GH, your body will eventually realize this and do something about it. Whether or not it makes much actual difference has yet to be determined. Jin kits always cost more, the 192aa GH uses an older, cheaper form of production called "Inclusion-body technology" I believe, which leaves and extra amino acid on the end of the chain. Still works well, but your body eventually notices the difference and can develop antibodies against that 192aa stuff. However, I've not tried it myself, so I will not pass judgement. I will say that, given the price and the length and dosage at which I'd need to run it, I'm afraid to take that kind of risk with something i'm not SURE is 191aa like Jintropin, when the price difference between the two is relatively small.