Sanitary Manhole Cover(pressure manhole, sight glass) Export to USA, UK., tank manufacturer since 1996. ISO9001- ... 2008 APPROVED! Sanitary Manhole Cover(pressure manhole, sight glass)Dimensions: 250*100mm -600*120mmThickness: neck 5mm, cover 4mmPressure ... and dairy and chemical industry, Sanitary Manhole Cover(pressure manhole, sight glass)