tech drive very-quiet 80 cfm, 1.5 sone no attic access needed installation bathroom ventilation and exhaust fan tech drive <b>how to choose your bathroom fan?</b><br><br> <b> what is a sone rating?</b><br> sones, or the sone rating, is a term used to describe sound levels. lower sone ratings are found on quieter fans. higher sone ratings indicate a louder bathroom fan.<br><br> <b>what is cfm? </b><br> cfm (cubic feet per minute) measures fan air movement. cfm increases as air movement increases. a higher cfm is best for a larger bathroom; a lower cfm may be adequate for smaller spaces.<br><br> td-bf-01 110cfm/1.0sones. ventilating for bathroom up to 110 sq. ft <br> td-bf-02 90cfm/0.8sones. ventilating for bathroom up to 90 sq. ft <br> td-bf-03 70cfm/2.0sones. ventilating for bathroom up to 75 sq. ft<br><br>td-bf-04 80cfm/1.5sones ventilating for bathroom up to 85 sq.ft<br><br>td-bf-05-l with led light ventilating for bathroom up to 75 sq.ft.<br><br>td-bf-06 70cfm 0.3sones ventilating for bathroom up to 75 sq.ft <br><br>td-bf-07 with humidity sensor ventilating up to 110 sq.ft<br><br>td-bf-08-l with led light ventilation for bathroom up to 85 sq.ft<br>