Aromasin is the best AI these days. Arimidex is quite popular, but it is inferior to aromasin in every regard. Aromasin is a suicide inhibitor, so it will permanently deactivate the aromatase enzymes, and no estrogen rebounds will take place with it. Also, unlike arimidex, it will improve cholesterol levels, not get them worse. The best places for aromasin are sarms1.com and ag-guys. The usual dosage is 10 mgs EOD.