Basically, I'm just using a 1/2 inch insulin pin and want to make sure that I put it in any area that the fat is thin enough to reach muscle. For me, quads are super lean, year round, so they work just fine. These shots aren't as big of a deal as IM oil based gear shots. I just try to avoid areas that I want to do my AAS shots, to avoid added aggravation to those sights. So Tri's are a good place for me