Flexible PVC dock wheels are designed to rotate around standard 1.5" dock pipe. Made of heavy duty marine grade vinyl with wear resistant center axlebushing. Wheels can be placed over standard 1.5" diameter pipe for use as free floating boat guides or can be mounted to any custom dock bracket whichuses 1.5" diameter pipe. Wheels can be stacked together for added protection.Molded from UV resistant, Marine Grade Vinyl14" Diameter with 2" inside diameter reinforcement bushingInflation valve to adjust firmness