This Phat IGSPM136 6-inch duct muffler mini will make your indoor gardening fans and carbon filter systems significantly quieter and can reduce noise heard from room to room. Building Code compliant, it's easy to install and maintenance free. Simply position the muffler in new or existing duct work between the source of noise and the register emitting noise. This duct muffler is made of metal and is lined with UL listed, Class 1 Air Duct acoustic insulation that reduces sound. The insulation is covered with wire mesh to keep it in place. Support brackets not included.