Every first aid kit list sold online is built for someone else's trip.
Someone else's activity. Someone else's skill level. Someone else's distance from help. You buy the pre-made kit, you add the stuff some guy on YouTube told you to to add, and you carry it around for years and either begrudge how big and heavy it is, or open to find what you really need isn't in there. 
 
Instead of handing you a packing list, this book teaches you a system — the same category-based thinking that makes the Ten Essentials Framework work for a desert day hike and a winter expedition alike. Learn the categories, when to pack for efficiency or redundancy, and you can build the right kit for any trip, any environment, any length of time, any group.
Inside, you'll learn:
The category framework — an endlessly adaptable system with still-comprehensive coverage
How to decide whether your kit should be built for redundancy or efficiency (and why it matters)
How to figure out what to bring, and just as importantly, how much of it
How to scale a kit up or down as your trip, group size, and distance from help change
 
Ali (the author) as been a Wilderness First Responder with fifteen years of managing medical emergencies in remote places across seven countries — and a whole lot of opinions about gear. She teaches Wilderness First Aid- and this book was borne from her students asking her "Can you send us a list of what's in your kit?" and her responding "Well, that depends...."
 
Build a kit that fits the adventure you're headed out on. Not somebody else's.