When the StudPop Magnetic Stud Finder passes over a nail or screw that's embedded up to 1/2-inch deep in sheetrock, plaster, lath, tile, marble, metal studs, even stucco, its 'popper' stands straight out in the middle of its small, speaker-shaped housing. On sheetrock, the device's 1-inch magnet also emits a 'thud' sound and will stay attached at the exact spot on the wall or ceiling where a fastener is found. Being one-piece and made with ABS polymers, the Studpop resists breakage and requires no batteries or calibrating.