... to duct, no affect airflow. 4" high efficient duct muffler 1.uses,reduce the noise of the device.2.easy ... install.3.Easy to connect to duct, no affect airflow.Muffler (Muffler) is to prevent the sound and allow the air ... to eliminate air dynamic noise of the important measures. Muffler is installed on the air power equipment (such as ... distance transport and storage. 4 inch mini Efficient duct muffler