... installed on the air power equipment (such as fan, air compressor, boiler vent, generators, water ... inquiry. Product informationRemarksProduct name Efficient Duct mufflersize 4" miniDuct mufflerFine structure ,Practical, Strong,Appearance ... working environment2.ues for air power equipment (fan, air compressor, boiler vent, generators, water ... transport and storage. 4 inch mini Efficient duct muffler