I think it's funny that they name this thing "Antminer airflow noise reducer." This is just a duct muffler that's made for the hydroponics industry. This particular one is made for a 4in duct which may be a little bit undersized for any real performance. You may be better off getting a 6 inch or 8 inch duct reducer to connect to the 4in ducts on the antminer and then use a 6 or 8 inch muffler. Of course for maximum silence, you would need to build a wooden box around antminer and also use insulated flexible duct. Then you should be able to get the noise level down to next to nothing.the Hydroponics industry has been doing this for decades. They have had to utilize massive fans to cool the extremely hot metal halide or high pressure sodium lights that they use and do so in an extremely quiet way so as not to raise suspension of law enforcement.