Abstract: The inventive apparatus permits the connection of hoses to connecting pieces, which have a threaded, a ribbed, or a smooth end.The apparatus comprises three parts, namely the threaded part 1, the hose part 2 and the locking ring 3. The threaded part 1 always remains firmly connected to the connecting piece and thus shields its outer surface (particularly in the case of glass parts) against damage. The hose part 2 always remains connected to the hose. By brief turning, e.g., to the right, the two parts can be firmly connected by means of bosses 5 and slots 4 having mutually engageable serrations, but can be easily detached again by briefly turning in the opposite direction, e.g., to the left.Connecting pieces having non-threaded outer surfaces, i.e, with ribbed or smooth ends, can be fixed and sealed in the threaded part 1 by means of an O-ring or hose portion pressed between the locking ring 3 and the threaded part 1.