Coupling for pressure lines

The coupler (1) has a plug part (4) lockable against loosening via a bolting device (12). The bolting device comprises of a radial pre-resting recess (14) and a complete resting stage (18) of one of a housing part (2) and the plug part (4). The stage is displaced in a contact area of a resting element, around a radial misalignment (X), against a holding flank (22) of the recess such that a radial surface covering is enabled between the resting element and the holding flank of the recess during transmission between a pre-resting position and a complete resting position at an insertion movement. The holding flank and the complete resting stage are designed as radial surfaces or inclined surfaces. The resting element is designed as an elastic spring clip, which is designed as a molded part made of plastic.