Porter Disposable Breathing Circuit (DMC-5301-6). 6ft. single patient use disposable breathing circuit designed for use with the Nitronox HD model (or Nitronox unit equipped with the HD Retrofit Kit - available free of charge). The breathing circuit easily connects to the demand valve mounted on the side of the Nitronox device. The pink corrugated tube connects from the breathing circuit to the Nitronox Scavenger reservoir. The coaxial (tube within a tube) tubing allows for the mixed gas to travel through the inner tube to the patient and the exhaled gas through the outer tube an into the scavenger reservoir. A one way valve prevents exhaled gas from being rebreathed by the patient. The Nitronox Disposable Breathing Circuit can be used with either a face mask or mouthpiece.