A device (1) with a device holder (2) and a device insert (3) is described. The device holder (2) has two holder side walls (5a, 5b) which are situated opposite each other and are spaced apart from each other and oriented obliquely to the base plane (4) with respect to a common base plane (4). The holder side walls (5a, 5b) form, together with the base plane (4), a trapezium in cross-section. The device insert (3) has two insert side walls (7a, 7b) which are situated opposite each other and spaced apart from each other and are oriented obliquely to the base plane (6) with respect to a common base plane (6). The distance of the two insert side walls (7a, 7b) from each other increases from the reference plane (6) to the terminal edges of the insert side walls (7a, 7b) which are situated at a distance from the reference plane (6). The reference plane (6) is trapezoidal such that the reference plane (6) of the device insert (3) is oblique with respect to the reference plane (6) of the device holder when the device insert (3) is installed in the device holder (2) and the insert side walls (7a, 7b) bear against in each case one holder side wall (5a, 5b).