The surface-mounted box (ie the plastic part) is on the sides a little tight advised (space for the screws), because the cable feed of data box is laterally. This means that the cable has to be pretty bent. With a can I then this placeholder for the screw a little worked with the milling machine to allow more space for the cable is there.
But please make sure that afterwards not screw that secures the data can be screwed into the cable ....