Medical gas apparatus and instruments, namely, central gas distribution units in the nature of centralized medical gas distribution systems consisting of gas cylinders, gas containers, tubing, valves and ports for the delivery of oxygen, nitrous oxide and medical gases to multiple locations within a medical facility, stabilizers in the nature of stabilizer devices to stabilize and maintain pressure in medical gas cylinders and containers, pressure monitors, regulators in the nature of devices to regulate air and gas pressure in medical gas cylinders and containers, flow measuring devices in the nature of devices to measure gas flow in medical gas cylinders, containers and gas delivery systems, gas outlets in the nature of devices to release, capture and transport medical gases in medical gas delivery systems, valves for use in medical apparatus and instruments in the nature of valves to control the flow or release of medical gases in centralized gas delivery systems, cut-off valves in the nature of valves to stop the flow of medical gases in medical gas delivery systems, and speed couplings, namely, parts of medical apparatus and instruments, all sold as a unit for medical applications