Stanley Fatmax Stud Finder 400 Manual - Verified

If you have plaster walls, tile backer board, or thick drywall (5/8 inch), standard mode may not work.

The “400” designation means it has 400 levels of sensitivity adjustment, which is why calibration is critical. stanley fatmax stud finder 400 manual verified

Open your manual to the "Calibration" page. A verified manual will explicitly state: "Do not calibrate over a stud." If your manual omits this, it is a generic copy. If you have plaster walls, tile backer board,

For professional users and safety inspectors, here are the direct compliance notes from the manual: If you have plaster walls