The industy's first... and still the best. SensAire fans incorporate advanced sensor technology to automatically activate in response to motion and/or rapid rises in humidity. 9 1/4'' x 9 1/2'' x 7 5/8'' high housing. 11 1/2'' square styled plastic grilles. Fits4'' round duct. Units with lights are Type IC. Bulbs are not included in lighted units.