Broan-Nutone 164 Bathroom Heater/Fan Combination Unit, This 70 CFM/2-bulb heater/fan combination unit features quiet, highly-efficient polymeric blower wheels and dampers that eliminate metallic clatter while preventing backdrafts. Polymeric 4-inch round duct connectors with tapered sleeves provide easier, positive ducting, adjustable mounting brackets with keyhole slots that span up to 24 inch. 3.5 Sones, UL Listed, uses 250W BR40 size infrared bulbs (not included).