4" square 3-1/2" deep, concrete boxes with (8) 3/4" side knockouts & raised ground are installed in walls and ceilings where extra depth is needed for speakers, strobes, signals and other electrical and electronic notifications/alerts. Speaker (SPKR) boxes have extra-long external mounting tabs allowing the box to be nailed or screwed to wood or metal concrete forms. Garvin Industries’ labor saving design eliminates the need to awkwardly install boxes and extension rings to accommodate deep, devices