This is a cannula ("can NUH lah"). When the prongs on the cannula are placed in the nostrils of a person like me, who is short of breath because of a chronic lung disease, it delivers supplemental oxygen.
I went on oxygen at the end of March. There's a lot of learn. The most important is: "Don't trip over the green-tinted fifty-foot tubing," which connects the cannula to the oxygen concentrator. Alas, once a klutz, always a klutz. The second most important: you must clean the cannula once a week and replace it when necessary.
Only one had been delivered. I needed a spare for when the old one was drying after cleaning. I called the supplier.
"What size do you need?"
"Gee, I don't know. How many sizes are there?"
"Two. Size 14 and Size 17."
"I don't know what size I have."
"OK, I'll send you one of each and you can decide which one you prefer."
UPS delivered the cannulae the next day. I carefully measured the distance between the prongs with a ruler, using both the edge with the inches and the one with centimeters. Many times, from different angles. The distances always looked the same! I laid a new cannula on top of the old one. They looked like twins. How could that be? I tried measuring again. I was about to ask the resident mathematician for help, but decided to consult the Internet first.
Silly me! I learned that the cannula tube that connects to the green oxygen-supply tube is either 4 or 7 feet long. The 4-foot tube is for children; the 7-foot, adults. I looked at the packages. Sure enough, one was labeled 1600-4 and the other, 1600-7.
I don't know how the person on the phone came up with 14 and 17. Maybe that "1" was really an "l" (el), meaning "length?"
