... 3,Apperance is polished 4,manhole with pressure and without pressure square manhole cover with pressure 1,Type:Circular,square,elliptic 2,With ... pressure or without pressure 3,Material quality:AISI304,AISI316LFineness:Inner surface mechanical polish Ra ... dull polished Ra<0.8um square manhole cover with pressure,stainless steel manhole cover,sanitary manhole cover