Prohormone-free Animal Stak was launched over nine years ago, and though the formula was cutting-edge at the time, non-hormonal, anabolic supplements utilizing natural hormone boosters were still in their infancy. Animal Stak has long been built on being a complete anabolic hormone stack. It's not just a testosterone booster. It's also a GH booster and an anti-aromatase. Stak also contains specialized hormone amplifiers and restorative nutrients to optimize ones internal anabolic environment. It is extreme and all-encompassing, just like every pack in the Animal line.