Arrow asp-1, pneumatic exhaust muffler, sintered bronze, 40 micron, 1/8" npt, 300 psi, 10 pack arrow pneumatics sintered bronze pneumatic exhaust mufflers - these filters utilize porous sintered bronze directly bonded to a nickel plated steel pipe thread fitting to diffuse air and muffle noise from the exhaust ports of valves, cylinders and air tools. These units offer a combination of small size with the greatest possible sound deadening qualities to reduce exhaust noise to acceptable levels within osha noise requirements. Standard unit contains a 40 micron element and 20 or 90 micron units are available on special order.