Ergonomic Design: The seat is filled with thickened ultra-high-density sponge has good rebound and can perfectly fit the curve of the body. The curved ergonomic back and wide seat design provide comfortable support. It can reduce the fatigue caused by sedentariness. Weather-Resistant and Waterproof: Covered with high-quality PVC material, With tight stitching, it can effectively prevent accidental tears. It has excellent water resistance and abrasion resistance. Besides, the smooth and soft surface improves comfort. Durable and Stable Design: Heavy-duty rust-resistant aluminum alloy hinges prevent the backrest from bending and making it capable of standing up to the shock of great waves. The base is made of a high-impact plastic injection-molded frame with a strong load capacity of up to 250 lbs. Easy to Fold and Store: The aluminum hinge design makes it can smoothly flip up the backrest when needed for a comfortable seat, and fold it down to create more space when not in use. (Hight Back Dimensions: 24″H x 19″W x 15”D, Low Back Dimensions: 21″H x 21″W x 15.5”D) Easy to Install: We provide detailed illustrated instructions to allow you to quickly complete the assembly. What’s more, the 5″ x 5″ bolt-hole pattern allows you to easily mount the seat to any standard 4-bolt swivel or base (base not included).