This economical device detects nails and screws with its magnet sensor. The Stanley stud finder provides you with a dependable way to detect wall studs. A magnet works to locate steel nails and screws used to hold drywall together. You can renovate easier and move walls around faster with this home-improvement accessory. An improved useful tool for locating wall studs easilyMagnet is attracted to steel nails used to hold drywall to studdingBase of the stud finder is grooved for marking once studs are located1-3/8 in. x 1-3/8 in. x 1-1/4 in.