Fastening system

A fastening system (1) comprises a rear grip part (5) for insertion into a mounting opening (4) of a mounting rail (2) in a first position and for engaging behind the retaining projections (6.1, 6.2) in a second position, and with a stop (3) for end outside acting on the mounting rail (2). The stop (3) is connected to the rear grip part (5) by means of the screw (9). Further comprising means for inducing a relative rotating motion between the limit stop (3) and the rear grip part (5) about the axis of the screw (9) is provided on the fastening system (1). The device is designed as a transmission mechanism for converting a translational movement of the screw (9) relative to the stop (3) into a rotational movement of the rear grip part (5) relative to the stop (3).