Sewer smell inside your RV or your boat If you have ever had a fo ul smell in your RV boat and you can not figure out where it was coming from This waterless waste check valve may be can help you Allows water to flow through it but does not allow it OR sewer gases to go the other way It is a check valve of sorts Prevents fo ul odour or sewer gas entering the building Protects basements and other low level areas from the backflow of sewer storm sewer Dimensions: 186.2mm x 61.2mm 7.33 x2.4 (LxW). Dia: 2 fits for 2 interface Please further check your interface dimensions before make order Package Includes: 1 x Waste Valve