Not sure I've seen it on here in this summised fashion, but the following is something
@Type-IIx posted in his Discord about E2 management r.e EQ and Mast.
"Boldenone (EQ) is an aromatizable androgen. Practically, while its use can (often) lead to sub-normal estradiol (E2)_, since it suppresses endogenous testosterone (T)/E2 and aromatizes at only a small fraction of the rate (Vmax) of T to estrone (E1) & E2. E1 is a weak estrogen, with only 2% E2's ER-α potency. The degree to which EQ aromatizes to E1 depends on 17β-HSD isozyme expression, under genetic control.
Learn More in the Primo / Equipoise Crashed my E2 – Help!" article. So, while practically, using EQ can cause symptoms associated with low estrogens (e.g., joints aching, malaise), it is not a consequence of its inhibiting aromatase since it actually aromatizes!
Drostanolone (Masteron) is an aromatase inhibitor, and also prevents estrogen uptake into cells or tissue (e.g., synovial cells [joints], breast cells [antigynecomastic]) in a tissue-selective manner. Evidence of Masteron's aromatase inhibition can be found here:
Authoritative evidence that AAS with saturated A-ring structures (e.g., Masteron, Primo, Anavar, Superdrol, Proviron) all inhibit aromatase"