Offered is our replacement for the Seakeeper Heat Exchanger 40420-2.1SP. This heat exchanger is guaranteed for fit and function with equivalent materials used in the construction. This part replaces the OEM Seakeeper for the M7000 and the M8000.  That unit is designed for crafts from 50 to 59 feet long or up to ~30 tons. Please make sure that this part matches your configuration and feel free to call with any questions.