WhisperValue® DC™ FV-0510VS1 Fan is the perfect multifamily solution; also ideal for single family and manufactured homes. As the lowest-profile ENERGY STAR® certified fan available, it actually fits in a 2x4 stud bay. The low profile, 3-3/8” housing depth and unique L-shaped bracket allow this fan to be installed virtually anywhere - in ceilings or walls. The revolutionary DC motor with intelligent self-adjusting SmartFlow™ technology senses the amount of resistance in the duct run and automatically adjusts the fan speed to deliver the optimal CFM output, even in the case of a complicated duct run. The Panasonic DC motor with SmartFlow technology moves more air using less energy, so the fan is more energy efficient and lasts longer. Built-in Pick-A-Flow™ speed selector provides the unique ability to select your required airflow (50-80-100 CFM) with the simple flip of a switch. Being able to choose the proper CFM level gives you the flexibility and assurance that one fan will satisfy a range of ventilation design requirements and perform as promised, even with a complicated duct run. The extremely thin profile WhisperValue DC fan opens up options for where you can install the fan, which is UL listed for ceiling or wall mount. Installing a vent fan in a wall means that you won't need to cut a hole in the fire-rated ceiling and then buy a radiation damper to meet fire-resistance requirements in the building code. In a multifamily housing development, this means Big savings. When you have a household or business to run, you don't want to have to replace little things like a vent fan. Panasonic fans use less energy to move larger volumes of air than other brands. Consequently, Panasonic fans run cooler so they last longer. They are also much less likely to overheat and result in motor failure. The motor is also equipped with a thermal-cutoff fuse. Unique L-Shaped bracket simplifies installation and provides strong support. The L bracket is interchangeable to be positioned to either the left or right side stud for optimal fan placement. Optional 4 in. Oval to 3 in. Round Duct Adapter(FV-VS43R)* is available to give you flexibility in duct layout and design. Panasonic fans are also UL listed for tub/shower enclosure (just install them on a GFCI-protected circuit). With these great features, your installation options open up. * Refer to the Accessories Tab for more information on the 4 in. Oval to 3 in. Round Duct Adapter(FV-VS43R), sold separately. Panasonic ventilation fans are ENERGY STAR® certified, where guidelines exist. ENERGY STAR® vent fans meet strict parameters set by the US Environmental Protection Agency (EPA). They provide better efficiency and comfort with less noise, and feature high performance motors and improved blade design, providing better performance and longer life.