All Dolphin roto-molded fenders are manufactured from the best quality marine grade vinyl resulting in superior strength, cushioning and a high gloss finish. Dolphin fenders have been tested for many years in various marine environments worldwide. Dolphin fenders resist deterioration from mildew, gas, oil, seawater and bacteria and have built in ultra violet inhibitors. All fenders include an inflation valve to allow for adjustment for the desired level of firmness. Each center hole fender is equipped with central tubing to allow end-to-end line passage. The unique ribbed construction gives strength to the fender, minimizes rolling and offers maximum protection.