Phat Muffler, 6" x 13" MiniPhat Muffler is the best noise silencer on the market because it consists of an 85% Noise Reduction Coefficient (NRC). It is engineered to lower the noise of the exiting duct and inline fan. This unique glass pack noise reducer has aluminum construction for quick hanging and to prevent rusting. The 45 degree inner taper reduces more noise. It can fit into your existing ductwork or new ductwork perfectly. To dampen the sound of your inline fan, use