RectorSeal’sClean Check extendable backwater valve’s upper and lower collars accommodate both 4” and 2”diameter PVC risers. It features a 75-psi-rated (at 177’ of head) heavy-duty flapper. The snap-in/pullout flapper can be installed and locked into the lower collar. The flapper/collar assembly, riser and upper collar are lowered into place and locked into the valve body and outer riser’s slot channel with a counter-clockwise quarter-turn from ground level. The tight-sealing, plasticized PVC flapper is available for 3”, 4” and 6” diameter sewer lines.