This fits existing storm drain sleeves. 4″ x 6″ PVC Hub x Hub Reducer Coupling is used to connect 6 in. sewer and drain pipe to 4 in. sewer and drain. Use it in conjunction with the French Drain Man 4″ Corrugated Pipe Adapter to 4″ PVC.
4 in. x 6 in. PVC Hub x Hub Reducer Coupling