Letrozole is also known as Femara. It is 10-30x more effective than Arimidex in its ability to pass thru the cell membrane of lipid (fat) cells and inhibit the activity of aromatase -- in other words, Letrozole is far superior in lowering estrogen levels in fat cells. This has two benefits for BBs; (1) Estrogen 'attracts' water, so less water retention. (2) An average BF% for a lot of bodybuilders is around 6-10%, that's a lot of lipid cells with aromatase inside them, so a substantial percentage of aromatase is left untouched by Arimidex due to it's poor ability to enter lipid cells. Arimidex is approximately 80% effective at inhibiting aromatase, Femara is around 95-97% effective. Arimidex serves its purpose for a lighter cycle, but Letrozole is the newer science for some heavy duty gyno prevention and recession. It will be on sale this week here:
http://ar-r.com/shop/product_info.ph...products_id=42
Thanks,
Lion