MET-Rx Nitric Oxide Synthesis Pumped is a Neuromuscular Stimulator that provides a burst of energy with Caffeine to accelerate workout intensity. Arginine is an amino acid involved in the formation of Nitric Oxide, which can help support circulation. Glycerin may help support body hydration. Our Extreme Nitric Oxide Synthesis Pumped Complex also contains Citrulline Malate.