The Bull BBQ (16505) replacement main burner large knob is constructed of durable zinc plating with a chrome finish, fits all Bull BBQ gas grills (any size). To install, simply detach main burner control knob by pulling directly out and replace with new. Installation takes less than 1 minute. Sold individually. 24-Inch Bull Grills require three(3) grill knobs, the 30-Inch Bull Grills require four(4) and the 38-inch Bull Grills requires five(5) grill knobs.