Our stainless steel bore caps are manufactured by us in Australia, they will not rust.   The standard bore cap will safely fit all bores with a bore casing internal diameter of 220mm or less and this model has a 50mm female BSP thread in the centre together with a slot for cable access and 2 x 316 stainless steel eye nuts to make lifting easier.   We laser cut the round plates from 304 stainless steel sheet, brush the face so they are neat and burr free then we attach the 1 x 50mm stainless socket and 1 x 50mm stainless steel elbow with a length of heavy brass allthread secured with liquid sealant.   The 316 stainless steel eyes are secured with M10 x 40 stainless set screws and the complete unit is then packed ready for dispatch to you.  Strong and much safer & easier to lift out, the stainless steel will not rust and comes with a 25-year warranty.