Clinical studies show glucosamine sulfate is a key building block for connective tissue and cartilage. The glucosamine sulfate in doctor-recommended GS-500 is up to 98% absorbable which makes it more readily available to the body to support healthy articular cartilage. GS-500 is the original glucosamine sulfate product in the United States-the standard by which all the rest are judged.Other products from HerbsPro