This is a cable concealer designed to hide the cables that go from the devices to the TV.
It consists of two parts, the base that goes on the wall, either with adhesive tape or 4-5mm screws and the cover that clips onto the base.
It also has loops so you can tie or tire-up the cables so they are stable and guides so that they fit straight over each other.
On the 3mf I have two tops, one as in the pictures and the other with rounded edges.
The dimensions are:
Width: 56mm,
Height: 25mm
Length: 150mm