Carrier HT32CH231 Crankcase Heater 319852 301 Universal T 4000 Series Compatibility: Fits Universal T 4000 Series Compatibility: Fits all standard horizontal T 4000 series pneumatic thermostats Durable Construction: Built with a high quality cast brass body and a molded synthetic rubber diaphragm for a constant effective area throughout the full 11 16 inch stroke Ensuring this electric resistance heater is operational is essential for "long line" applications where the system charge exceeds standard limits It can be utilized on smaller diameter compressors provided the band is tightened securely to ensure direct thermal contact with the shell