Safety Seal Muscle Strength Dietary SupplementDiscussion: Pro Muscle Nitric dietary supplement is a combination of Di-Arginine Malate and Citrulline Malate. Di-Arginine is a precursor in the formation of Nitric Oxide. Nitric Oxide aids in the delivery of oxygen and blood to the muscles which may benefit your workout and lean muscle mass. Citrulline is converted to Arginine in the body.