The powder-coated steel construction and button switch are very well built, and there is no noise or crackling when pressing the switch.
It also has two screw holes on the bottom. This makes it possible to mount it upside-down underneath a desk or on a wall for example. You screw the black part of the case into the desk, and then attach the blue part to the black part using the four screws on the side (shown in the picture). It would have been more stable if there were four holes on the bottom instead of two, but it works reasonably well.
Note that it does not mute the sound completely, but reduces it by about -60dB. Sometimes this can make a difference.