Masteron is an injectable preparation containing the steroid drostanolone propionate. Drostanolone is a derivative of dihydrotestosterone, most specifically 2alpha-methyldihydrotestosterone.Masteron doesn't aromatize - it can't be converted to estrogen. Drostanolonum is highly androgenic and a strong anti estrogen with minimal liver toxicity, it is usually used as a part of cutting stacks for the last few weeks of contest preparation, it works best in stack with Primobolan, Anavar, Winstrol and Testosterone propinate ( Testovis ).