... .Easy to connect to duct, no affect airflow. 4" high efficient duct muffler 1.uses,reduce the noise of the device ... ",6",8"and12".Welcome to your inquiry. Product informationRemarksProduct name Efficient Duct mufflersize 4" miniDuct mufflerFine structure ,Practical, Strong,Appearance perfectMaterials1 ... .Helpful for long distance transport and storage. 4 inch mini Efficient duct muffler