Don't quote me, but i think the thing with it is that it binds to SHBG , which in turn frees up more more of your total testosterone in your body, which is why it gives you the good results, cause now you have more free test to do its "thing". Well SHBG also binds up Estradiol, but I think to a lesser degree than it does so with testosterone. Anyhow, now you have higher levels of free test. and also higher levels of estrogen. Higher test or should I say free test levels, also means higher chance for aromatization, and now more estrogen. Again don't quote me on this, but I think it goes somewhere along the lines. Hopefully one of the experts or more knowledgable on this topic guys will add to this, or correct me if I'm wrong.