Best Glucosamine Sulfate contains pure glucosamine sulfate, as confirmed by HPLC testing. Glucosamine sulfate consists of glucosamine, an amino sugar extracted from shellfish skeletons. "Chitin", the resilient polysaccharide that forms the structural framework of animal shells, is a long-chain polymer consisting of many glucosamine molecules linked together. The purified glucosamine is then sulfated and stabilized with potassium chloride. Note: Best Glucosamine Sulfate is sodium-free. It contains 24-26% potassium chloride.