a first connection stub having a first free end for receiving said first hose; and

a second connection stub having a second free end for receiving said second hose, wherein said first hose has an inner diameter that is smaller than an inner diameter of said second hose, wherein said second connection stub is provided with a shoulder at which, in a direction toward said second free end, a diameter of said second connection stub, decreases from a first outer diameter to a second outer diameter, wherein said first outer diameter is larger than said inner diameter of said first hose, and wherein said shoulder is formed by a wall that extends approximately perpendicular to a longitudinal central axis of said second connection stub, so that said first hose is capable of being pressed onto said second connection stub from said second free end up to said shoulder, where said first hose is adapted to abut against said shoulder, and said second hose is capable of being pressed over said shoulder onto said second connection stub, and wherein a cylindrical portion is disposed on said second connection stub and extends all the way from said shoulder to said second free end of said second connection stub.