Sony DMX-NV1 Operating Instructions (For DMX-NV1 model sold separately) Operating Instructions Manual page 24

Getting Started
24
The bottom Mounting Knob thread in the hole and the top Mounting Knob sits on the
groove.
4
Lightly push the receiver down so that both Mounting Knobs are locked
into place.
Make sure that cables are organized with the Cable Cover so that the
cables hang out on the same side as the Mounting Knobs and on the
front side of the receiver.
If difficult to mount the receiver, remove the TOP Mounting Knob.
Reposition the receiver to the bracket then tighten with the Mounting
Knob to keep in place.