These are an improved version of the wall mount brackets for a Vizio soundbar.  These are based on the mounts that came with model SB36512 but will probably work for other models. 

The original brackets had an open back which dug into my plaster wall when securely anchored to a stud.  My version has a solid back so they won't sink into the wall.

The soundbar also seems to sag down some with the original mounts.  I have a 5° version which angles the mounts up 5° to remove the soundbar sag.

My original brackets after 2 years of use.  One broke and the other sunk into the plaster wall: