The area outlined in red protrudes from the mount and causes a gap between this mount and the adapter plates, only where the bolts holes are. In other words if you set this mount on a flat surface, there would be a gap between the flat surface and the bolt holes. I happened to find a set that was recessed and allowed it to set flush on the adapter plates. Which left me with no gap between the adapter plates and the bolt holes. Although I don't have mine together yet. This is what I noticed when looking at my setup. This may not even matter... just my .