1、Stainless Steel: The filler cap is made of 316 stainless steel, rustproof, with high polish, brightness and flatness to withstand the harsh environment at sea, with maximum resistance and durability in saline water environments. 2、With Key: The convenience of having a special key specifically for the boat fuel fill cap offers enhanced security and easy, reliable access to your fuel system. 3、Leak Proof Seal: The rubber sealing ring ensures a tight seal between the cap and tank, preventing leaks and enhancing the overall reliability of your fuel system. 4、Versatile Compatibility: Compatible with a wide range of vehicles including boats, yachts, caravans, RVs, trucks, tractors, and trailers, making it a versatile and practical choice for all your fuel tank needs 5、Easy Installation: Fuel fill cap features a caliber of 48mm and an outer diameter of 50mm, making its installation a breeze. This user friendly design saves you time and effort, allowing for a fuss free and smooth installation process.