The YORK® by Johnson Controls model CRDE is a high quality, low silhouette, centrifugal roof exhauster. This completely self contained powered ventilating unit is ready for easy installation on a variety of factory built and field built curbs. The most significant factor that sets this model apart from conventional roof ventilators is its low-line extruded aluminum housing. Crisp, clean lengths of full width blades are mitered at the corners and welded on the underside to present a clear, unbroken sweep. In addition to its clean appearance, the louver blade is designed to reduce friction and the turbulence of exhausting air.