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. Motor is thermally protected and has a water-hardened motorized impeller. 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 ARN25K Radon Mitigation Fan Kit includes an ARN25F Fan, one ARN05M Manometer, two ARN64C Couplings (6-inch x 4-inch), and one ARNALM Radon System Alarm. The ARN25F measures 11.75 inches W x 8.6 inches H and is ideal for most sub-slab radon mitigation systems with a basement or slab size between 1,500 and 2,500 square feet*. It has a 6-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.