These are the standard light weight Cannulas that fit the Portable model Inhaler Adapter (Not same as for our (Hydrogen Inhalation machines). These are non-crimping flexible tubing Soft-Touch nasal Cannulas with standard universal connector tips and curved, non-flared nasal prongs that minimize irritation and soreness when worn for hours at a time. Each Cannula is 6 feet long (1.8 meter) and are long lasting. We recommend you change your Cannula every 60 – 90 days depending on how often you use our inhalation machines. Comes in convenient 4 Packs. It is recommended not to share a Cannula for sanitary reasons and use masking tape to write names on and tape to tubes to avoid sharing others by mistake.