A novel design for the connection of lengths of polyvinyl chloride (PVC) casing. Each length of casing has a male end and a female end. The female end has a narrowing interior diameter with its wider interior diameter at its outermost end sufficient to receive the male end of similar length of casing for connection. The diameter of the female end narrows to a diameter which is less than the outer diameter of the male end. The male end has a lip at its leading edge and is slotted and compressible when forced through the narrowed diameter of the female end. A groove in the interior surface of the female end is sufficient to receive the lip at the leading edge of the male end. When the lip at the leading edge of the male end reaches the groove, it allows the compressed male end to expand with the groove receiving the lip therein. The connected lengths of casing are locked together in this manner.