I prefer to carry a small set of EDC (“Everyday Carry”) supplies in a bag to provide me with various capabilities during my daily commute to work. In the past, these items were stored in a backpack and were organized by using color coded modules for the various categories of gear. The problem that I had with this approach is that it didn’t work as a system with my non-EDC kits, which are also stored in a backpack (e.g., Get Home Bag, Bug Out Bag). I can’t easily carry two backpacks. A few years back I made the switch to carrying EDC items in a single-strap sling / messenger style bag. This makes it possible for me to also carry an emergency backpack at the same time (if needed) and then leverage all of the individual gear as a system of supplies.