A container designed as a refillable cylinder used to hold compressed nitrogen (N2) under safe conditions at high pressure (e.g., 50 - 150 Bar). It is typically filled with nitrogen when delivered from the gas supplier and includes a valve stem, an opening/closing valve, and will be graded according to size (capacity) and colour-coded to denote nitrogen content. The cylinder is typically made of steel and must be used together with a pressure regulator in order to release the nitrogen at the correct working pressure. Nitrogen is typically used as a drive gas for surgical power tools (e.g., drills, reamers, saws) but can also be used in the clinical laboratory.