Mars Hydro iFresh 4" Smart Inline Duct FanDescription Premium Performance, Budget Friendly Price: The fan's core motor and blade specifications are fully comparable to those found in flagship models from competing brands. The smart controller features a USB based design that significantly reduces cable clutter, while the app provides advanced, customizable smart control strategies. Thanks to Mars Hydro's years of experience in the supply chain, this means you can get the best performance at