This is a Leveling bracket designed for the T-Rex pedal boards and raises your Wah pedal (or any double length pedals). Long pedlas can be tricky to fit on a board and are usually relegated to the floor. With htis addition to your board you can now keep your whole rig on the same mount.
You can install the bracket in a different horizontal position on your board from that shown, the boards have pre-drilled holes just for this purpose. The available positions vary with the board models but it fits the 45, 56, 70 and Major boards from T-Rex.