Abstract: A one-piece flexible plastic coupling for connecting a first conduit with a pipe of a second conduit has a central portion in the form of a bellows. The coupling has an end in the form of a cylindrical socket for receiving, an end of the pipe of the second conduit. The cylindrical socket has an inner surface with a diameter greater than an outer diameter of the pipe of the second conduit and an outer surface having a diameter defining a socket wall of predetermined thickness. The socket includes at least one protrusion extending inwardly from the inner surface of the cylindrical socket and extending around the entire circumference thereof.

Abstract: A roofing slab with vent opening which is arranged in a central region thereof and is limited by a peripheral edge collar and over which a cover extends in hood-like manner. A hose connection pipe directed towards a bottom side of the roofing slab is coordinated with the opening. The edge collar projects beyond the bottom side of the roofing slab and extends into a dish, and the hose connecting pipe projects on the bottom of the dish.