ðɪs fˈaɪndɚ mˈʌst fˈɜːst biː kˈælɪbɹˌeɪɾᵻd ˌoʊvɚɹ ɐn ˈɛmpti sˈɛkʃən ʌvðə wˈɔːl, ænd ðˈɛn ɪt kæn biː mˈuːvd ɐlˈɔŋ ðə wˈɔːl ʌntˈɪl ɪt sˈɛnsᵻz ɐ tʃˈeɪndʒ ɪn dˈɛnsᵻɾi sˈʌtʃ ɐz ðɪ ˈɛdʒ əvə stˈʌd.
This finder must first be calibrated over an empty section of the wall, and then it can be moved along the wall until it senses a change in density - such as the edge of a stud.