Plug-in piece

The plug-in piece (1) has a support pipe (5) with sealing areas (6) made of elastomeric material, and a fitting (7) with reduced permeation for water vapor. A radial flange (9) and a sealing lip are provided at free ends (8) of the support pipe, and a film covers the free ends. Sealing beads (13) are formed in the sealing areas such that two valleys (14) are formed, where each of the valleys is attached to the free ends. Hydrophilic substances (15) are arranged in the valleys and comprise drying agent and superabsorber.