Plug-in coupling

A coupling comprising:

• a base body being partially inserted into a tube end;
• a sealing element disposed on said base body;
• a sleeve comprising axially opposing anterior and posterior sleeve parts;
• said sleeve parts each including axially opposing anterior and posterior ends and an interior surface;
• said interior surface of said anterior part supporting the tube end;
• said sleeve parts being permanently and fixedly connected at a radial lip;
• a support body disposed on said posterior end of said anterior sleeve part;
• said support body including an exterior positioning surface disposed at a pre-determined angle so that a radius of said surface increases toward said anterior end of said anterior sleeve part;
• an annular gap disposed between said base body and said sleeve for receiving the tube end;
• said interior surface of said posterior sleeve part being spaced from said exterior positioning surface of said support body for forming a free space;
• a retaining element disposed axially against and radially exterior to said support body;
• said retaining element including a closed annular part disposed radially adjacent to said radial lip connecting said sleeve parts;
• said retaining element including elastic retaining claws disposed against said exterior positioning surface of said support body for fixing the tube end to said coupling;
• and
• said retaining claws being movable in said free space.