Sorry about the picture being sideways!
Fire extinguisher I believe that kind has carbon tet.
Paul is correct. Here in Australia they came in a number of sizes. That is the smallest one. There was another of the same diameter but twice as long. then they grew in diameter. They are pressurised and work when you hold them with the valve to the bottom and the knurled knob is opened to let out the fluid.
I have used one twice, very effective, but probably not legal anymore, having the wrong stuff being liberated into the environment.
I have a polished larger version, complete with mounting bracket, on the dash of my 1917 shooting brake, just for decoration.
Allan from down under.