Zerostart 8605556 Heavy Duty Engine Block Immersion Heater for Caterpillar, Detroit Diesel, International/Navistar and Perkins Engines, 1" NPT Thread | 120 Volts | 1500 Watts Ensure quick winter starts and reduce engine wear CSA Approved For Caterpillar, Detroit Diesel, International/Navistar, and Perkins engines. See Zerostart catalog for specifics 120 Volts/1500 Watts Thread Size: 1in NPT