Vacuum Exhaust Mufflers Porous Plastic Mufflers Model No. M-38/30 ANVER Part Number Exact Replacement For P-Series Muffler No. AThread NPT BDiameter in. (mm) CLength in. (mm) Filter Size Microns Weight oz. (g) M-38/30 N375FF 3/8″ 0.95 (24.1) 2.70 (68.6) 30 0.20 (5.67)