To mount this unit to the wall, we'll be using a French Cleat wedge bracket
. This is little more than a 2x4 which is ripped down the middle at a 45-degree angle. One half of the ripped piece will be mounted on the wall, and the other half inside the cabinet.
First, cross-cut a clean, straight 2x4 to 46-1/2" in length.
Next, set up your table saw with a ripping blade and tilt the arbor to a 45-degree angle. Raise the blade until it is at least 1-1/2" above the table. Set the fence so that the bottom (against the table) of the cut will be one-inch wide. Lay the 2x4 flat on the table and carefully rip it the entire length. You should end up with two identical wedges at 46-1/2" in length.
One of the two wedges will be attached under the top shelf of the cabinet with the 2-1/2" side to go against the wall (when mounted) and the wedge pointing downward. Use two 3" screws to attach the wedge to each standard, and a few 1-1/2" screws down from the top shelf into the wedge.
Next, mount the other French Cleat wedge against the wall. Use 3" screws to drive it into wall studs with the 1-inch side of the bracket against the wall and the wedge pointing up. Be sure to level
the wedge so that the cabinet will be level when mounted.
As you can now see, the advantage of using the French Cleat wedge bracket system is that the bracket in the cabinet will sit on the wall-mounted bracket, and the angle of the wedge will force the cabinet's weight toward the wall.