This Duct Muffler can make your indoor gardening fans significantly quieter, and can reduce noise heard from room to room. The 8 inch Duct Muffler (for use with same-size ductwork) reduces noise by up to 25 dBA; a reduction by 3dBA cuts a listener's perception of sound by half! These Duct Mufflers are easy to install, connect to existing ductwork, do not restrict airflow, and require no maintenance. Support brackets not included.