The Trane KIT19191 Accessory Kit with Piston and Stub Tube is a replacement component kit designed for compatible Trane HVAC systems. It includes a piston and stub tube that work together to regulate refrigerant flow through the refrigeration circuit, supporting proper system operation and heat transfer. Commonly used in compatible Trane air conditioning and heat pump equipment, this ... https://www.partshnc.com/kit19191-trane-accy-kit-w-piston-stub-tube