I've used stud finders before but this one surprised me with it ability to locate studs under my homes 1-1/2" thick combination gypsum board/plaster walls (in the 1950's they called them lath-less plaster walls, consisting of 1/2" gypsum board, covered with 1" of hard-as-rock plaster). Easily allows centering on wooden studs and as a bonus, helps you avoid those pesky electric wires apparently ran at random through the wall studs.