This Mueller 429-010 1 Coupling PVC Slip X Slip is a slip coupling made of PVC. It is designed to connect two pieces of PVC pipe. It has a male end and a female end. The male end has a slip fit and the female end has a slip fit. This coupling is perfect for use in water or gas systems. This Mueller 429-010 1 Coupling PVC Slip X Slip is a slip coupling made of PVC. It is designed to connect two pieces of PVC pipe. It has a male end and a female end. The male end has a slip fit and the female end has a slip fit. This coupling is perfect for use in water or gas systems.