The Star Mfg 2R-Z1854 Black Pointer Knob 1-7/8\" DIA Mount 0.25\" Round is a rotary control knob used on compatible commercial foodservice equipment for adjusting operating settings. Its pointer marking indicates the selected control position as the knob is turned. The 1-7/8-inch diameter provides a suitable surface for manual rotation, while the 0.25-inch round mount connects with the matching control shaft.