A deployable hospital that manufactures its own oxygen appears, at first inspection, to have solved a logistics problem. Moving compressed gas and liquid oxygen into a theatre where roads are contested and airheads are scarce is among the harder tasks a medical supply chain is asked to perform, and a container that separates oxygen from ambient air removes most of that traffic. The reasoning is sound enough that it has driven procurement in several European armed forces and is the organising claim of the suppliers who serve them.