When it comes to your gear bag, real estate is precious. You want carry whats important and necessary - but nothing more in the effort to stay fast and light. One of the best outdoor related purchases we have ever made is the SAS Survival Guide by John Wiseman. There's so much information in such a small space that we keep a copy in every GO Bag we have (and we have several) for those "What If" SHTF scenarios. It doesn't matter if we are hiking, biking, or heading deep off grid - this book is with us.
Sure some of you will say "well I already know most of that." The question is will you remember it? In times of stress, things tend to be fuzzy. You forget things that you should know. Your mind will go blank and this book will remind you how to identify snakes and wild plants (with color pictures), multiple ways to start a fire, trap animals, find water... all in the size of a stack of index cards. If it's too thick for you, the pages are glossy and sturdy enough to tear out what you feel is important so you could laminate them to make a small set of guide cards.
Another question to ask yourself is: will the person you're with know as much as you? We can just about guarantee that someone in your party will not. Maybe they haven't had the medical, survival, or military experience that you possess - and if your'e the one in need of help you need that other party to step up to the plate to save your life.
The SAS Survival Guide is small enough to fit in the cargo pocket of tactical pants, the glove box of your car, or in a super light minimalist hiking bag like we show here. The only remaining question should be why would you not buy this book? It's the perfect size to fit in every backpack, bug out bag, or INCH Bag.