The MRCOOL MCAEHWD5X1AA Signature Series Air Handler Heat Kit 5kW - R454B is an electric heat kit designed to provide reliable supplemental heating for compatible MRCOOL Signature Series air handlers used in split-system heat pump HVAC applications. It works by generating electric heat that automatically supports the heat pump during colder temperatures or when additional heating capa... https://www.partshnc.com/mrcool-signature-series-heat-kit-mcaehwd5x1aa