These Shutter Fans are great for exhausting larger sized rooms and spaces.  Remember when using these fan that for every cubic foot per minute exhausted, you will need to allow for proper make-up air to enter the area you are exhausting.  To calculate proper ventilation, divide fan cfm by 750 to give you an idea of how much sq. ft of venting you will need. Click Here For Photo Of Front Grills Model SF1276-1: Requires at least 1.01 sq. feet of net free venting Model SF1612-1: Requires at least 1.66 sq. feet of net free venting Model SF2030-1: Requires at least 4.164 sq. feet of net free venting. Please make sure adequate make-up air  is supplied when running any exhaust fan.  The potential for back drafting can occur with these type exhaust fans.  That means devices such as gas water heaters and gas furnaces in the same rooms as these exhaust fans,  where there is no source of make-up air will pull air from the path of least resistance.  This could include, your water heater vent pipe, furnace vent pipe, etc.  The potential exists that gas from these appliances could also be pulled into the area you are exhausting.