Cliff Bars are great, but they just aren't packaged for long term storage. I take them for day hikes all the time, but I don't think the material they use for the sleeve they are packed in is very high quality. The Millennium Bars, are in some kind of foil/poly hybrid material, the way MRE's are packaged, and they seem to be designed better for long storage under widely varying conditions. Lifeboat rations are like that too.