The YORK® CI model of ceiling exhaust fans operate quietyly. Some selections are available with sound ratings below 1 sone. There are 15 types of models that cover a wide range of performance. The units are easily field convertible to change the discharge orientation from right angle to top discharge. They are also easily field convertible from ceiling (model CI) to inline (model CI-TDA) installations. There are multiple sizes that utilize two speed motors that allow these units to cover an even greater range. All motors are equipped with thermal overload protection as standard.