Bought a set of these over Christmas. You don't get much in the packaging i.e. 2 x plastic L-Shape holders, a couple of screws and links to instructions so on the face of it it doesn't look much for the money, however, they hold the board very well. I had to switch the screws for different ones due to the stud walls in our house but all-in-all very pleased.
Attached are 2 pictures showing the board hanging vertically (ignore the paintwork on the wall – it's a WIP 😉 ) and one showing a close up view of the mountings. Essentially the one on the right is slightly loose to allow it to twist at a 90 degree angle to allow the board to be mounted/dis-mounted with ease. The board could easily have been mounted diagonally as per the instructions given but due to lack of space and slight concern about solidness of mount it was put vertically and out the way of the bed. After positioning this way I'd say I'd be happy to mount horizontally, diagonally or vertically as the board fixings and the weight of the board holds it solidHTH.T.