These are all Valterra check valves which are available with a swing/spring combination. Sizes for the check valves range from 1/2 inch up to 6 inches in size. All springs are set with 1/2 lb tension. You have the ability to select check valves that are clear which enable you to see the water as it flows through the valve or you may select the traditional solid color (white). There are two fitting connections of slip x slip and FPT x FPT.