Engineer John Blake invented StudPoP® magnetic stud finders after he found that electronic versions rarely work as advertised.His simplified tools don’t need batteries or calibration to work. Just run one along a wall, and the indicator will pop up and click. StudPoP®s contain very strong magnets that do a much better job of locating studs than electronic ones that struggle with thicker walls found in older homes. StudPoP®s can even detect a metal fastener in a stud through a wall up to half an inch deep. Now hanging things like a mirror, picture frame, or shelves is easier, in any type of construction including plaster, wood lath, tiles, wood or metal studs.