The Alen BreatheSmart Air Purifier 4-Pack offers 4400 square feet of allergy coverage with $239 in savings. Each unit includes your first, easy to replace HEPA-Pure filter. The Alen BreatheSmart Air Purifier makes cleaning the air simple. The BreatheSmart uses Alen's SmartSensor Technology to detect airborne allergens and pollutants, automatically adjusting airflow to protect you while saving energy and extending filter life. The BreatheSmart 4-Pack is both powerful and quiet, providing up to 4400 square feet of coverage with Alen's WhisperMax Technology, a specially designed fan and air chamber that maximizes clean air delivery while minimizing noise. That means you can enjoy both pure air and a peaceful environment.