21x27inch Square Deck Hatch Heavy Duty Aluminum Alloy Push Out Ventilation Porthole for Boat Yacht Ship RV 1High Durability: Made of heavy duty aluminum alloy, the anodized, polished surface offers a good matte touch, and guarantees corrosion resistance and durability, robust enough to resist the harshest marine environments. 2Smoke Tinted Tempered Glass: Features 6mm thick smoke tinted tempered glass, the tinted color can filter out UV rays while letting in light, thereby improving cabin brightness, can also serve as a ventilation window. 3Waterproof and Shockproof Design: The frame of the deck hatch is equipped with a waterproof sealing ring, offering perfect sealing waterproof and shockproof performance when the window is closed. 4316 Stainless Steel Support: The supports and hinges constructed of 316 stainless steel, ensuring overall corrosion resistance and durability, the push out opening design allows for any angle opening from 090 degrees. 5Versatile Fit and Application: Measuring an exterior size of 21x27 inches and requiring an installation hole size of 18.4x24.4 inches, ideal for boat, yacht, ship, and RV, can be used as a skylight, escape window, storage, roof and more.