Mishimoto MMTS-CHV-01DH Chevrolet/GMC 6.6L Duramax High Temperature Thermostats (set of 2), 2001-2016 Fits 20012013 Chevrolet/GMC 6.6L Duramax Activates at higher temperature allowing engine temperatures to rise Allows for cooler engine temperatures Purchase Includes: One 185 F Thermostat / One 191 F Thermostat Mishimoto Lifetime Warranty Thermostats activate at a higher temperature than the OEM thermostats Allow's the coolant to stay in the engine longer