I've been in EMS for almost 30 years now, the last 20 as a Paramedic. I've carried some extensive first aid kits, but recently I have been paring mine down a little. One thing I stress for people to carry is simple things. Moleskin for blisters. Ibuprofen and Aspirin. Lots of bandaids. Sure you should carry something to stop major bleeding, but the reality is you will probably need more bandaids than tourniquets. The two most important things are having some good first aid training, and having a way to shout for help in the back country. Having a bomber first aid kit does you zero good if you don't know how to use it. Wilderness First Responder is a fantastic class and it will teach you how to improvise first aid with what you have on hand. When it comes to calling for help, lots of folks carry Spot or the Inreach units, but they require a hefty subscription on top of the device. I have been carrying a Personal Locator Beacon. A PLB is the same device as an ELT in an aircraft or an EPIRB on a lifeboat, except this one you carry in your pocket. You pay one price (around $250) one time, and you have to register it with NOAA so they know who to contact if it goes off. When you do fire it off, it doesn't go through a private satellite system like Spot etc. It goes through the world wide COPASS-SARSAT system that is dedicated for search and rescue world wide. The transmitter also transmits a signal on 121.5 Mhz that aircraft can use to direction find your location. The only recurring cost is the battery replacement and testing every 5 years. It doesn't do text messages, or send out a tracking signal so your fiends can follow on the internet. It is a single purpose rescue device that will get you help on any continent or any ocean in the world. That's my 2 cents. I would be more than willing to answer questions on the forums, but there is no substitute for taking a solid wilderness first aid course of some kind.