The wedge is relatively thin and made of sturdy black plastic. It is the same length as the part of the bracket that goes against the wall, do it blends in and looks like it's part of the bracket when installed. It (optionally) goes between the wall and the bracket.

The brackets can be adjusted to rotate your speakers horizontally or tilt them vertically. My speakers are pointed straight ahead (no toe in) and are tilted downward slightly. I found that the vertical tilt increments provided by the brackets alone weren't fine enough for my tastes, so I ended up using the wedge thick part up behind the brackets in order to point the speakers downward to the exact angle I wanted.