The J-S15 Sump Valve is designed to fit into and become part of your sump cover. It is a one way valve that allows water to flow into the sump but prevents Radon Gas, soil gas, insects and odors from entering your living environment. Installing the JS15 requires cutting a 2-inch hole in your sump cover. The JS15 sump valve then bolts to the underside of the sump cover using the alignment collar which protrudes around the top of the JS15.