A2-Pump is an esterified form of arginine (C15H22N4O3HCl), designed to penetrate the lipid membranes of muscle cells where its unique molecular structure increases nitric oxide production. The result is full, hard, pumped muscles. The effects of A2-Pump are noticeable within just a few days of use. It increases muscle pumps, escalates vascularity, improves muscle hardness and definition and provides noticeable results within just days.