$MADE BY: SPEEDAIRE Exhaust Muffler NPT 1/8 Inch, Hex 7/16 Inch, Length 1 1/8 Inches Item Exhaust Muffler-1A325 Type Pneumatic NPT Port (In.) 1/8 Max. Pressure (PSI) 300 Microns 40 Element Material Sintered Bronze Fitting Material Nickel Plated Steel Hex (In.) 7/16 Length (In.) 1 1/8 Function Reduce Exhaust Noise Levels to Acceptable OSHA Requirements at 18:23:19 PDT, the following:.