Philips Respironics 22 mm tubing, or (15) for the Philips Respironics 15 mm tubing. When using Heated Tubing, the device will automatically change this setting to the appropriate tubing type (15H). Tube Type Lock This enables you to lock the Tube Type setting for either the 15 mm or the 22 mm tubing if you do not want the patient to change it..