I tried 31G, 29G, 28G and 27G and very much prefer 27G for sub-q injections, at least for now, but I'm just starting, so it may get old quickly. I do 0.15 mL Test Cypionate Cottonseed Oil (Perrigo) and with 27G it flows extremely easy. Even with 28G drawing was sloooow....Pinning doesn't feel...