New Ecofit high-efficiency E-Series backward-curved impellers are now available in both 115 and 230-V models in the popular 250-mm (9.85-in) size. The new 250x50R impellers offer significant increases in airflow and major reductions in operating noise levels compared to other backward curved fans. They also provide a wider operating temperature range and ERP 2015 efficiency compliance.
Ecofit E-Series fans feature special airfoil blades made from UL 94 V-0 reinforced plastic. Their unique design allows for 33% greater airflow at 1.2-inches of static pressure while reducing noise levels by 6 dB(A). This is a very significant reduction, as noise levels double every three dB(A).
Motors for the new fans are CE approved and UL recognized. They are 100 percent speed controllable. Thermal contacts provide motor protection to Class F.

Specs can be downloaded here: 
1) 2RREU45 250x50R_Q13-A1_120V.PDF 
2) 2RREu45 250x50R_Q13-A0_230V.PDF