The MRCOOL HHK-15 ProDirect Series Top-Discharge Electric Heat Kit is a supplemental heating accessory designed to provide additional electric heat for compatible HVAC air handlers. It works by using electric heating elements to generate warm air, which is distributed through the ductwork by the air handler when extra heating capacity is needed. Designed for use with compatible MRCOOL... https://www.partshnc.com/mrcool-prodirect-series-top-discharge-heat-kit-hhk-15