Unfortunately I'm going to be the bearer of bad news. This mostly comes down to a quality issue. But let's use known sources and Rips for example as allot of the members on this board including myself has had good responses from the Rips provided by sources here. It all depends on your goals as stated by Irish and also depends on weather or not your injecting multiple times a day subcutaneously or if your injecting maybe with a slin pin intramuscularly. Here is something that I've wanted to share with all of you as this just came up in question from my friend who is an ifbb pro bbuilder and we just talked about this last week. Some of you know who he is but I'm not going to get into that...OK, here's a quick hint, he's doing the Arnold Classic this year for the first time. Anyway, here's something he said. He would only pin 10iu's if he's doing IM but if for some reason he has to pin Sub-Q, he'd pin any where from 15-20iu's split into two or three doses through out the day. Someone for him and in his position, believe it or not, they do get into a bind quite often where they can't just pull the needles and vials out and inject themselves. But here's something to keep in mind too, most pros or advanced bodybuilders will never even reconstitute to put in the fridge. He was telling me that he just reconstitutes then injects the whole 10iu's or 8ius or 4ius depending on brand or product on hand. So that was long winded but I thought some of you should know that as I have always wondered that myself. And it totally makes since too, doesn't it. There was a study done showing growth hormone secretion and blood levels using serum tests for IV, IM and SQ. I will try and find the source but it was something like this.... IV=100%(do not try this as pro's don't even do this), IM=85-95%(often being in the low 90's) and SQ=high 70's to low 80's more often being low 80's(obviously this includes site injection, bf% and a few other factors). Anyway, hopefully this helps a little.