Rosenberg new high efficiency, low noise I-Series Gen 3 EC plug fans deliver up  to 70% efficiency. Our Gen 3 EC motor operates at high efficiency, even in partial loads, and is paired with our new, advanced-design aluminum I-impeller, featuring five backward-curved, profiled blades and an efficiency-optimized circumferential diffuser. Noise levels range from a high of just 89 dB to a low of 68 db while creating up to 12% more air than earlier models.