The MRCOOL HHK-05 ProDirect Series Top-Discharge Heat Kit is a supplemental electric heating accessory designed to provide additional heating capacity 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 heat is required. Designed for use with compatible MRCOOL ProDir... https://www.partshnc.com/mrcool-prodirect-series-top-discharge-heat-kit-hhk-05