Calculated Industries 8120 Plug Mark Drywall Electrical Box Cutout Locator for Existing Electrical Outlets in Rehabilitation and Replacement Work Magnetic tool locates existing electrical outlet hole cutouts in rehabilitation and drywall replacement installations Perfect sheetrock cutouts in half the time with no measuring using powerful rare-earth magnets Get professional results you can be proud of your first and every time with this foolproof patented technology Pays for itself by avoiding costly and embarrassing measuring errors Two included targets fit any standard 3-prong Plug outlets, powerful locator finds targets, shows perimeter of box to be cut