... the noise of the device. 2.easy to install. 3.Easy to connect to duct, no affect airflow ... reduce the noise of the device.2.easy to install.3.Easy to connect to duct, no affect ... as fan, air compressor, boiler vent, generators, water pumps and other vent noise larger equipment) of gas flow path ... (fan, air compressor, boiler vent, generators, water pumps and other vent noise larger equipment)3.gas flow path ...