With everyone on holiday, and the weather turning colder, we see an increase frequency of very small steel and aluminum cylinders show up for recharging.
These cylinders were first developed decades ago driving the gas for soda making machines. Today they drive a thriving sport called paintball.
The cylinders are DOT-monitored just like our scuba cylinders, but apart from their size, differ most often in that they are filled with low pressure liquid Carbon Dioxide or CO2.