WhisperValue ENERGY STAR rated performance-valued exhaust fanswith light fixtures feature totally enclosed AC condenser motors for long-life and energy efficiency. This low profile model has a 3.75 inch height and operates with 4 inch oval duct. One 32-Watt compact fluorescent lamp and one 4-Watt night-lamp are included with an ENERGY STAR light fixture. Complies with Green building IAQ standards. The perfect marriage of efficiency and convenience, new features and technologies make the latest generation of Panasonic ventilation fans perfect for many ventilation applications. Whisper quiet operation and outstanding performance are achieved through our aerodynamic fan design technology. This new approach uses features like a tapered Sirocco fan to deliver improved ventilation excellence. These design and engineering improvements were made specifically to reduce already incredibly low sone levels.