Nairn inspection ports are manufactured to high tolerances using premium materials to provide high strength, durability and watertightness even in the most demanding applications. They all incorporate "O" ring seals. Rims and coloured lids are made from ABS plastic while polycarbonate plastic is used for clear lids to give both high transparency and impact resistance. EPDM rubber is used for superior weathering characteristics. All rims have wide caulking flanges and are screw in. The removable kit bags are made from woven nylon and feature corded closures for added security of stored items.