This invention relates to a device for mounting in a fixed mounted frame (7) on a subsea pipe comprising a locking device comprising a sensor housing (6), a spring (2) surrounding the sensor housing (6), at least one wedge (1) placed in one of the ends of the spring (2), and a edge (5a) placed in the other end of the spring (2), where the sensor housing (6) is arranged to be guided into the mounting frame (7), and that a force (13) is applied in the longitudinal axis of the sensor housing (6) so that the spring (2) is compressed and the wedge(s) (1) are spanned radial out towards the mounting frame (7) to center and support the sensor housing (6) in the mounting frame (6), the sensor housing (6) is designed to fit into the mounting frame (7).