Carrier high efficiency air filter for heat pump, air conditioner and gas furnace applications. This cartridge style air filter is easy for the homeowner or do it yourself handy man to change out. Carrier offered this style of filter in 2 brands when they first started producing them. You could purchase the air filter branded as a Bryant filter using part number beginning with FILBBCAR and FILBBFNC. They were also offered as a Carrier brand with the part number beginning with FILCCCAR and FILCCFNC. When Carrier decided to stop offering 2 different part numbers they changed the part number to begin with FILXXCAR and FILXXFNC with XX replacing BB for Bryant and CC for Carrier. The letters FIL designate a cartridge style filter. The CAR designates the filter is used in gas furnace applications and the FNC designates the filter is used with a heat pump or electric furnace application. The 00 after the CAR or FNC desinates a merv 8 rating. Carrier offers this filter in a higher merv rating but we do not sell them as we believe they are too restrictive to air flow and may shorten the life of the equipment if not serviced properly. The last 2 digits in the part number designate the nominal width of the filter cartridge. Notice there are 2 sizes that are very similar, FILXXFNC0024 and FILXXCAR0024. the two filters are no he same size.