The side wall of the cabinet was notched and relieved to allow the L-pads to fit. I brought the foilcal out to the edge rather than recessing them 3/8", again this is a personal preference for a clean looking baffle. It also gave me more room for the grille frame. It was rather difficult to line up the mounting holes to the attenuator board, I had to massage the holes on the first one to fit but got this one right on the first try. Hidden behind the foilcal it should be A-OK