City Gravity Water Hatch comes with both city and gravity fills and is built for convenience. No doors or locks and mounts in a low profile setting. Easy installation and comes with our new replaceable plastic city water fill check valve. Built with a 1/2 inch screened air vent to make filling your fresh water easier. cut out dimensions 3 3/4 inch height x 6 inch width Outside Dimension. 5 5/16 inch height x 7 9/16 inch width.