NO2 Black is the first patented extended-release nitric oxide generator designed to deliver upper limit nitric oxide all day long. It is enhanced by the patent-pending ACTINOS2 technology. ACTINOS2 was developed to increase NOS (nitric oxide synthase), the rate-limiting factor in the human body's ability to generate nitric oxide. With more NOS, NO2 Black delivers upper limit nitric oxide for massive gains in lean mass, "in-gym" muscle recovery, and skin ripping pumps. NO2 Black is also enhanced with alpha lipoic acid to help you keep your muscle gains.