Rubber O Ring from Allen, designed for Hatch covers.
Hatch covers Rubber sealing ring for A.337/A.337W Nylon inspection hatch covers in black, grey or white. We have three different designs, A.137 and A.237 are non 'O' ring original design with exposed fixings, the A.337, A.537 and A.637 require a rubber 'O' ring and the more rigid A.737 and A.837 feature a fully threaded cover with integral seal.