Hydro Crunch 4 inch 188 CFM Inline Duct Fan & 4" x 12" Carbon Filter Hydroponic Ventilation Set Hydro Crunch 4&quot; Inline Fan &amp; 4&quot; Carbon Filter Combo 4&quot; Inline Fan with Built-In Free Variable Speed Controller x 1 4&quot; Carbon Filter x 1 Removes odors and airborne carcinogens Easy to use and install