My basic kits for typical local rides. These get stuffed into my center jersey pocket.
Road…
Includes a $1 bill for tire-booting. That specific one has already proven itself in that capacity, and has stayed in my kit.
Gravel…
For races/events, I add a second tube and a third CO2 cartridge, and will most often use a small saddle bag for this stuff. I also carry a hydro pack that has a mini pump inside.
MTB…
For longer rides where I use a hydro pack, the bag clips to the outside of the pack.
I need to add tire booting material for my gravel and MTB kits.