Not sure, exactly.. But on the subject of coffee, let me plug for a good new product at Gander - I'll have to look at the name when I get home.. but they are these sealed cups that self-heat and make coffee within the cup in 3 or 4 minutes. You flip it over, press a button on the bottom, flip it right side up.. and you will hear it start to sizzle.. When the pink circle on the side of the cup turns white, it's hot and ready to drink! Shake, open, and enjoy. They are really neat, and the Mocha is delicious. Run about $2.25 if I recall correctly.. would make for the perfect fix while out deer huntin!