1.uses,reduce the noise of the device. 2.easy to install. ... no affect airflow. 4" high efficient duct muffler 1.uses,reduce the noise of the device.2.easy to install.3 ... ) of gas flow path or into the exhaust system, reduce the noise device.We have types of muffters,about 4 ... equipment)3.gas flow path or into the exhaust system,reduce the noise device,Prevent noise pollution4.Simple structure, practical5. ...