Goods is unfortunately incomplete: Coupling and rubber gasket as a back lid (closure) is used, there are two parts. This cover has 3 screws (holes are provided and fit) are connected to the coupling. However, these were not necessarily required screws on delivery. In the complaint to himself Amazon reported immediately and very friendly. However, could a subsequent delivery of screws not be offered, instead, only the withdrawal. I'll now have to visit a hardware store to pick out the suitable screws according to pattern, so I can use the product.