... "20mm/ 25mm knockouts color : white Square stamping conduit box 1) name:switch box, 2 gang box , 1 gang box,flushing box,surface box2) sizes: 3"x3",3 ... of construction ,electrical equipment , components12)PVC 2 gang box are used as surface mounting ,control box , switch box or general service box 3x3 box , pvc material ...