Kirkland Signature Extra Strength Glucosamine & MSM, 375 TabletsKirkland Signature Glucosamine with MSM Dietary Supplement. Extra Strength. Joint Health. Glucosamine is a basic building block for cartilage, synovial fluid and other connective tissues, which are needed for healthy structure integrity, and function of joints and optimum mobility. MSM (Methylsulfonylmethane) is a bioavailable sulfur. Sulfur is a necessary component that works in conjunction with Glucosamine to provide the building blocks of collagen,