WALLS-AND-CEILINGS VALUE PACK includes both the Blind Mark for standard single or multi-gang wall boxes for NEW construction; plus the Center Mark which locates 4, 5 and 6-inch recessed cans for accurate ceiling cutouts BLIND MARK AND CENTER MARK MAKE LOCATING AND MARKING outlet boxes and recessed lighting cans easy; they find boxes/cans behind drywall so you can outline them for perfect cutouts with less lifting and NO measuring