Panavise 861 CCTV 2.5-Inch x 2.5-Inch Square Base (Black) Square mounting base for solid surfaces, 2.5-Inch x 2.5-Inch (63.5mm x 63.5mm), with four 0.219-Inch (5.56mm) holes on 2.0-Inch (50.8mm) x 2.0-Inch (50.8mm) layout 0.25-Inch 20 mounting stud