Yoder Smoker YS640 UNIVERSAL THERMAL JACKETEach jacket is designed with five layer thermal construction to prevent heat loss that occurs as the temperature outside begins to drop, and therefore reducing pellet usage. Insulating the body of the cooking chamber, the thermal jacket is ideal for smoking temperatures of 300F and below. We recommend removing the three piece thermal jacket for those cooks above 300F, as it was specifically designed for smoking temperature ranges. This thermal jacket