Texas Pneumatic Tools speed control mufflers provide an infinite variation of metering air flow on the exhaust ports of the air valves, as well as adjust the speed of pneumatic devices, such as air tools or air cylinders. They operate at an acceptable sound level and are integrated with lock nuts to maintain the operating speed settings, thereby preventing any accidental adjustments due to vibration or other means. These screwdriver adjustment, exhaust port flow controls have surrounding sleeves of sintered bronze to eliminate exhaust air noises and are available in sizes of 3/4, 3/8, 1/4, 1/8, 1/2 and 1 inches.