Allen Access Door 145/200mm Black and White AllenBrothers - - Caution, gaskets must be ordered separately, ART1810Cut - out diameter 158mmOpening diameter 145mmOutside diameter 200mmColour: white or black Bag sold separately 157mm Hatch Cover. This is an externally sealed hatch cover. The gasket (body) is fixed to the hull of the boat and the A.538 O ring is placed around the gasket, under the small lip. The hatch cover lid is then screwed tight onto the gasket and forms a seal with the O ring around the external diameter of the hatch. Available in three colours and with or without a hatch bag. This hatch cover requires O ring A.538 to be installed for complete water tightness. PLEASE NOTE - A.538 is not included. EXTERNAL SEAL HATCH COVER - MEDIUM A.537 - Technical documents can be downloaded here