Reagent turning yellow indicates legit Ephedrine. 24hreup can be a bit more expensive than some others but at least I know it is 100% legit. I can usually tell just by taking it and then doing some sprints. If it makes me cough mucous Im pretty sure its real. But there are plenty of fakes out there, so Im happy to keep sourcing from 24hreup since I know it is 100% legit.