Test converts to estrogen. When we use test for performance enhancement, we increase our levels to much higher than your average level so there is much more conversion. We want high levels of test to grow muscle but we do not want high levels of estrogen which will bring on female characteristics. So yes, you need an Ai. How much you need depends on your dose of gear, how greatly your body converts test to estrogen and how sensitive your body is to Ai’s. The only way to be sure is to start out with a basic protocol for dosing and then do labs when things are stable. Also, along with your steroids, HCG produces test which will also convert so that needs to be regulated as well. Once you stop the gear at the end of the cycle, you can get weird instability in your test to estrogen ratio which can also spark issues while you wait to start PCT. For this reason you want to keep taking your AI up to PCT and you want to go into PCT with E under control for more rapid recovery.