Intex Mariner 4 Inflatable Raft River/Lake Dinghy Boat Set & Motor Mount Kit The strong molecular structure of this plastic makes it highly resistant to damage from abrasion, impact and sunlight. This special PVC plastic material also allows more air pressure for greater rigidity while maintaining the PVC material's natural flexibility. The Mariner 4's SUPER-TOUGH construction is made with 3 separate layers of 26.4 gauge (0.65mm) material - two outer layers of heavy-gauge pvc laminated to an inner layer of polyester mesh for extra reinforcement. The quality and design of this material results in extra strength and extreme durability. This reinforced PVC plastic is much thicker than comparable inflatable boats; the Mariner 400 Boat is built to get you there and back! Two Boston valve on main hull chamber for quick-fills and fast-deflations The keel is inflatable; this results in improved control and handling A durable rock guard lines the circumference of the hull above which an all-around nylon grab line circles the upper hull