... install. 3.Easy to connect to duct, no affect airflow. 4" high efficient duct muffler 1.uses,reduce the noise of ... device.2.easy to install.3.Easy to connect to duct, no affect airflow.Muffler (Muffler) is to prevent the ... ",8"and12".Welcome to your inquiry. Product informationRemarksProduct name Efficient Duct mufflersize 4" miniDuct mufflerFine structure ,Practical, Strong,Appearance perfectMaterials1 ...