This is which circuit:-

Baincircuit is a coaxial modification of the Mapleson D circuit. It consists of a fresh gas flow inlet, a narrow inner tube, a corrugated outer tube, a reservoir (breathing) bag, an adjustable pressure limiting valve and a facemask at the patient end. Itdoes nothave aCarbon dioxide absorberunlike the circle breathing systems. Rebreathing of carbon dioxide is prevented by an adequate fresh gas flow and by the presence of adjustable pressure release valve. The exhaled carbon dioxide flows through the outer corrugated tube and out this valve from where it can be scavenged. The fresh gas flows through the inner tube. When anesthetic gas inflow is much greater than the uptake by the patient and the circuit, excess pressure builds up, which leads to the opening of the adjustable pressure valve and expelling out of the gases.