The Hi & Dri II has been the standard for round tubedesign since 1981. It is unique in the fact that wheninflated, it takes on a streamlined shape on the sidesand forms a bow in the back of the boat which helpsyou move through the water more efficiently. Theinterior squares at the backrest, giving you morehip-room and expanding the patented adjustable seatto a roomy 20 width. There are two storage pocketson each side with one additional pocket on top of thebackrest. With a 40 diameter we have designed this boat forstability and comfort. The shell is a durable 420 denier nylon. 5 year warranty.