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 and bacteria and have built in ultraviolet inhibitors. All fenders include an inflation valve to allow for adjusent for the desired level of firmness.