The Bird Mark 4 is an anaesthesia assistor or controller with pressure and volume controller to be driven by a respirator. Combination of Mark 4 with respirator makes an automatic anaesthesia respirator eliminating manual bagging. The machine can work through Boyle anaesthetic system. It is designed for both paediatric and adult application. (Drugs and Equipment in Anaesthesia Practice, Aruna Parameswari, 2019)Green metal box atop a clear plastic unit with a black bellows inside, which forms one part of the overall unit. The unit is attached to a pole, enabling height adjustment. The pole is, in turn, attached to a set of four castors [not original].White text on black stick on strip on top of metal box: DO NOT PULL APART / FOR USE IN THEATRE ONLY A series of instructions are printed in white text over the unit.anaesthesia assistor, anaesthesia controller, pressure controller, volume controller, paediatric, adult