this is a estratrian derivativ.
closer to a 19 nor ((17 bêta)-17-hydroxyestra-4,9,11-trièn-3-one) but not the same formule at all.
is the reason than some person ( in fact realy rare got progesterone infuence with tren, while on the same time no gyno, cause basicly, after it pass the enzyme it cannot be converted as a oestrogen)