MSM is a sulfur donor and potent anti-inflammatory that has been successfully used by horsemen for years. It increases circulation, which reduces inflammation to damaged joints, allowing the horse to be more comfortable and mobile. It also gives the horse the sulfur he needs to produce collagen in the joints, and also to produce the hormones and antibodies he needs to function properly and stay healthy. Recommended as a joint supplement and overall health aid for all classes of horses. 99.8% pure.