I have more than one. There are several tools that I never leave home without.
I carry these tools attached to my boots, and if I ever take them out to use them I put them right back after, so I know they are always there. Since I always wear my boots when I go out, I know I always have the tools with me. I don't have to remember to take them with me or load myself up before going out. I wear my jeans outside my boots, so my tools are always concealed from view.
In pic 1 (left boot) there is a AA flashlight (Klarus P1A) and a stubby adjustable wrench (7/8" jaw).
In pics 2-3 (right boot) there is a Leatherman P4 in the little pouch, 6.5" adjustable pliers, and a Wiha micro bit driver full of specifically selected bits.
Every now and then I have a need for these items away from home, sometimes a vital need. I was out a few days ago and unexpectedly needed the flashlight in the middle of the day. If I go out at night I carry a light in my pocket, but never in the middle of the day. So having the light on my boot really paid off. Just one incident of many regarding my "boot carry" stuff.