Prime MSM contains methylsulfonylmethane, also known as MSM. MSM is a natural substance that is found in plants, animals, and humans. It is a sulfur-containing compound that has been shown to have many benefits for horses. MSM supports healthy joint function, promotes strong hooves and hair, and helps to maintain overall health and vitality. For more information, visit http://www.primeperformancenutrition.com/.