Fitment of 143F Thermostat NOT fit for DFI optimax motors. For Mercury Marine V-6 135-150HP S/N A904646 and later For Mercury Marine V-6 175 HP S/N C100861 and later For Mercury Marine V-6 200 HP S/N 6435503 and later Please check thermostat appearance before purchase. Specifications: Type: Thermostat Kit Material: Metal, Plastic Color: Black Brass Tone Fitment Type: Direct Replacement Size: 3x2.5cm/1.18"x0.98" Include 2x Marine Thermostat Kit Features of Thermostat Comp Water Come with reliable heavy spring, good abrasion resistance, reduce shock and ensure thermostat work well. Help to fix boat engine problems like overcooling, overheating, hiccups, coolant leak, provide a smoothful driving. Precise product shape for easily installation, no need to drilling or jointing. Please check professional video online if get in doubt during installation. This is non-oem product, acessory only.