Coaxial F-circuit is a system which results in warming of inhaled gas by exhaled gas. This circuit is 1.8m long and is the most commonly used rebreathing circuit in veterinary practice. It is recommended for use in larger patients (10kg+). For smaller patients, either a non-rebreathing circuit should be used or the paediatric smooth-bore circuit should be considered. The Kahuvet coaxial F-circuit Includes a monitoring port for connection with equipment such as side-stream ETCO2.