The Panasonic FV-10NLF1 WhisperLine 120 CFM In-Line Fan has a totally enclosed condenser motor and a large, double suction blower wheel to quietly move air. The blower wheel is designed to draw air in from both sides allowing more area for the air to enter the wheel. Panasonic fans are quiet enough that you might not even know they"re on. This fan is designed to give you continuous, trouble-free operation for many years due to its high-quality components and permanently lubricated motors which wear at a slower pace. We designed the electrical configuration of this model"s condenser motor to allow it to operate at lower temperatures, increasing the life of the motor and bearings. The fan housing is made of heavy-gauge zinc galvanized steel and painted to protect it from rust. This in-line fan fits a 4-Inch duct and can be installed in five different positions and joist, truss and suspension brackets are included to help make your installation as easy as possible. With a 1.0 sone level and rated 120 cubic feet per minute, this fan is Energy Star qualified. The Panasonic FV-10NLF1 WhisperLine 120 CFM In-Line Fan is covered by a manufacturer warranty for period of three years from the date of the original purchase and is sold one item per package. Panasonic WhisperLine fans are designed for multiple-task ventilation. This means that you can ventilate multiple areas or multiple rooms with just one fan. For example, you can place inlets over the shower, tub, toilet and/or vanity in a single bathroom and still use just one fan. In recent years, homes have become more airtight and energy efficient. While this lowers the cost to heat and air-condition a home, it also retains pollutants that can be hazardous to its occupants. One way to improve the air quality of the home is through whole-house ventilation with a Panasonic WhisperLine fan which removes stale air and provides fresh air on a slow, continuous basis.