A device intended to be used to measure and regulate the flow of medical gases [e.g., oxygen (O2), nitrous oxide (N2O), or air) from a gas supply to a patient during anaesthesia. The gases are usually mixed to the desired ratio by the operator using separate flowmeters for each gas; the mixed gases are delivered to the patient via a breathing circuit, but may be delivered singularly if desired. This device is typically mounted onto an anaesthesia unit, but may also be used independently (e.g., in a research laboratory setting).