Both of the two capitol "D" food grade hollow silicone gaskets. One sits on the lower flat part and one on the 45º section of the interlocking lip. Use black Permatex Auto silicone gasket maker to attach, installation instructions in the private KK forum owner's maintenance area.
We have them custom extruded out of a special high-tech, high-temp resistant food grade silicone.
The UPS delivery on this should be $14-15, if it comes back as $30 please write us and will help out
Use this to attach the gasket: Permatex 27037 Optimum Black Gasket Maker 3.35 oz