Abstract: A sprinkler head comprises a tubular body having a first threaded end to be connected to a water line and having a second end that defines an outlet enclosed by a cap. A thermally responsive element, such as a glass bulb or heat fusible element, is engaged with the cap to maintain the cap in a closed position. The body is provided with a pair of generally parallel circumferential grooves. The bottom of one of the grooves adjacent the threaded end has a polygonal cross section to receive a wrench to enable the sprinkler head to be threadedly attached to a water line, while the other of the grooves receives the base portion of a wire-form protective guard that encloses the thermally responsive element.