This bag does a lot of things ALMOST as well as others. It's okay to carry pistol ammo but not as good as the boxy canvas mechanic's bags. It can hold a 3" K frame Smith but not a 4"; a service size 9mm fits nicely, but for transport only. Once the zippers and buckles are in place, access is slow and clumsy (they never claimed it was a holster). I wouldn't carry a loaded firearm in it without a holster or other fitting to block fingers or small loose objects entering the trigger guard. Other fanny packs do better. It can carry first aid supplies but the openings are small and make it difficult to locate items, especially in the dark, when seconds may be precious. But it's a neat, interesting, seemingly well-made bag and as soon as I figure out what to do with it, I'm gonna love it.