Speed Control Muffler: Quiet Flow speed control mufflers provide an infinite variation of metering air flow at an acceptable sound level on exhaust ports of air valves with complete safety. With linear adjusting ability, the speed of an operating cylinder or air tool may be increased with the adjusting screw. The final position is then locked in place by the lock nut. Objectionable exhaust air noise is eliminated by the surrounding sleeve of sintered bronze.