I know its popular thinking on this board that Masteron works as an AI but my experience with it tells me otherwise. At the end of a 4 month cycle of 300 test /300 Mast and no AI, my estro was 160. Top of the range is about 115. Just putting it out there because I think some of these beliefs get started and perpetuated without any personal experience or bloodwork to back it up. I'd like to hear from people who've gotten bloodwork on mast and no other AI.