That way the stopper would pop out and turns the vial unstrile all over again. Besides when I get roids from others i dint see the stopper pinned anywhere. so how do they do it? it must be open vial filling, no?Also I like presealed sterile vials. Then run 18-20g pin right off the filter into sterile vial. What MG did you make? That will effect solvents as well