You have the opportunity of choosing three powerful ventilators. For smaller kitchens and canopies less than 3 ft. use RV-400. For large kitchens and canopies 3 ft.- 4 ft. use RV-800. For extra large kitchens and canopies 4 ft. or greater, use RV-1200. These powerful ventilators are equipped with backward inclined impellers that have superior suction for cooking odours, i.e. grease and smoke from heavy duty cooking. Due to a well balanced impeller motor, the noise level is less than 2.0 sones. Tests were done when each unit was installed 8 feet away from the hood.