The MRCOOL PHK15H ProDirect Series Heat Kit is a supplemental electric heating accessory designed to provide additional heating capacity for compatible ProDirect air handler systems. It works by using electric resistance heating elements to generate warmth, which is distributed through the ductwork by the air handler when extra heat is required. Designed for use with MRCOOL ProDirect ... https://www.partshnc.com/mrcool-15-kw-heat-kit-for-prodirect-series-phk15h