... power equipment (such as fan, air compressor, boiler vent, generators, water pumps and other vent noise larger equipment) of ... noise device. Product information RemarksProduct nameEfficient duct Muffler size 6 inch mini and 6inch Duct mufflerFine structure ,Practical, Strong ... 4.Simple structure, practical 5.Sound-absorbing effect:25DBA 6.Easy Install 7.No maintenance required. Packaging1.Whellote-box ...