These noiseless burners provide a clear flame of any desired height from 1/2" (12.7mm) to 12" (305mm), with separate control of both flame temperature and flame length. The burners incorporate threaded aluminum air control sleeves and precision machined, fine-pitch brass needle valves with internal stuffing box and self-sealing packings. Rustproof 3-1/2" (89mm) octagonshaped, plated die-cast bases and aluminum mixing tubes are also utilized.