Product Description Structure: Manhole frame+Safety Ring+Manhole cover Outline Rainwater inflow into manholes on sidewalks or streets requires pumping water causing awesome noise which gives people lots of troubles every year. So, a study has been carried out to get rid of above troubles. Features 1)Environment -The water does not enter into a manhole(Water pollution and groundwater pollution prevention) 2)Safety -Fixing a assist cover (Safety ring) can prevent casualties or car accidents by its upset, leaving, breakdown or abrasion etc 3)Waterproof -The rubber pack between the fixed cover...