Maradyne Marine Bus Heater Kit, 40,000 BTU, 12v, 3-Ducts, 15. 9" W x 7" H x 9. 6" D. Includes the following accessories: (1) 738567 MH-TA7000078 Switch Kit; (3) 738575 MH-TA8000462 Louvered Vent; (1) 738631 MH-4023005B Vent Hose 3 x 25'/Box; (1) 739012 MH-TA00079 Wiring Harness 9'. Heater box is made of non-corroding heavy-duty glass-filled nylon. Inner wall strengthening plates are threaded with 1/4-20 weld nuts. 12 volt 3-speed fan. Tested to SAE J1171 and ISO 8846. Meets USCG requirements for ignition protection. All hardware is marine grade. This uses 5/8" water hear hose to connect to coolant system. Use part# HMH-160-06250