Amarine-made Boat Yacht Elliptical Oval Opening Portlight Porthole 16&rdquo; X 8-5/8&rdquo; Replacement Window Port Hole - ABS & Black & Tempered Glass (A) 4mm thickness tempered glass. ABS Anti-aging, Anti-ultraviolet. Casted and polished 316 stainless steel accessories. Easy "click-in" construction. Corrosion free synthetic fittings and durable rubber seals.