1.uses,reduce the noise of the device. 2.easy to install. 3.Easy to connect to duct, no affect airflow. 4" high efficient duct muffler 1.uses,reduce the noise of the device.2.easy to install.3.Easy to connect to duct, no affect airflow.Muffler (Muffler) is to prevent the sound and allow the air through a device, it is to eliminate air dynamic noise of the important measures. Muffler is installed ...