They both came vacuumed sealed in a mylar bag. They both have a 5 year shelf life. And they both have a 'tear here' notch making them simple to open with no tools.
S.O.S Emergency Food Bar 1200 calorie
The SOS bar has 3 individually cellophane wrapped 400 calorie bars. Making it very easy to have a bar a meal. When I first opened it, I was very skeptical about how it would taste, but I was quite surprised. It tastes slightly of coconut and has the texture of a cookie or dry biscuit, without being dry. There is a slight grit to the texture, but it is pleasant. There were a few crumbs, but breaking a bar was simple and nearly crumb free. I had a bar for lunch and found that I was satisfied and didn't need to drink a gallon of water after. In fact, I didn't even have a drink with that "meal".
Mainstay Emergency Bar 2400 calories
The Mainstay bar was not sealed inside the mylar bag, but was portioned out. Breaking a square off was simple and relatively crumb free. The description says a 'pleasant lemon flavor'. It must be very mild, as I didn't notice lemon at all. It was like biting into a sugar cookie. It was very rich and turned slightly creamy as you chewed reminding me of cookie dough. I had intended on having this also for a lunch (on a different day), however after the second bite I started to feel like I had eaten too much raw cookie dough and couldn't finish eating it. I didn't feel hungry or thirsty though. It was too sugary/rich for me.
Then came the real test- The kids
WE HAVE A WINNER!!!!!
The SOS food bar was the clear winner for the kids.
The Mainstay bar was much thicker than the SOS and the kids couldn't get their small mouths around it. They had to bite the corners and that made for a lot of crumbs.
Both of the bars had great taste, but the S.O.S 3600 calorie is the bar that will be joining our 72 hr kits. I will be putting them inside a ziptop bag to keep them from getting wet or lost once opened.