Is your Yamaha Grizzly 660 (models from 2002 to 2008) running too hot or not warming up properly? This brand new thermostat from Celox could be the fix. It's a direct replacement for the original Yamaha parts numbered 5KM-12411-00-00 and 5KM-12411-01-00, so you know it'll fit right in. The thermostat is a crucial little part of your ATV's cooling system – it opens and closes to let coolant flow and keep your engine at the perfect temperature. This one comes new in its packaging, and it's made to meet OEM specs. Installation is usually pretty straightforward if you're comfortable working on your Grizzly; you'll typically find it in the housing where the upper radiator hose connects. Just remember to check for any gasket that might be needed. It also comes with a California Prop 65 warning, which is standard for many vehicle parts. Keeping your cooling system working right helps prevent overheating and engine damage, so this is a smart, affordable piece of maintenance to tackle. Make sure your model year matches before you order!