No I have not tried them but they look interesting.
http://www.askaprepper.com/make-2400...feed-full-day/These bars are often built in a 2400-calorie pack that is designed to feed you for a full day. The rations are often broken into 4 squares of 600 calories each. These rations are not only used by preppers and survivalists but backpackers and hunters utilize them as well. This is a testament to their efficiency as a calorie provider. Of course the elk hunter wants a delicious back strap for dinner but these rations are a nice second option.