AprilAire Radon Mitigation Fans are specifically designed for radon mitigation. They provide superb performance and run ultra-quiet. Whether a basement, crawl space, or slab on the grade, our fans and accessories can effectively remove radon before it enters the home. Radon is a naturally occurring odorless and colorless gas and is the #1 cause of lung cancer in nonsmokers. AprilAire Radon Mitigation Fans are energy efficient and meet all electrical code requirements. Water-hardened thermally-protected motor. Rated for commercial and residential use with a patent pending design. For indoor or outdoor use. Made in USA with US and Imported parts. The AprilAire ARNHPK Radon Mitigation Fan Kit includes an ARNHPF Fan, one ARN05M Manometer, two ARN33C Couplings (3-inch x 3-inch), and one ARNALM Radon System Alarm. The ARNHPF measures 11.9 inches W x 10.9 inches H and is ideal for most moderate to tight soils* where a high static pressure is needed to maintain continual air flow beneath the slab. It has a 3-inch Fan Duct Diameter. The ARN05M Manometer Mounts to the outside of PVC pipe and measures vacuum pressure in real time. The ARNALM Radon System Alarm is an advanced vacuum monitoring device utilizing piezoresistive pressure sensor (PPS) technology. It provides homeowners with an easy-to-read, easy-to-use system alarm that requires no interpretation. *Other factors play into fan selection, such as soil/grade type, home construction, etc.