That’s good.
I actually just read about the Calibration feature today, when I was replacing one of my temp probes. It is not actually a calibration of the unit, but it is an offset feature.
Basically, the unit on my 220 was still working very well, but it was reading about 4 degrees off from the digital thermometer I had on the tank. I keep a spare digital thermometer to check the others and used it to find out that the InkBird probe was at fault and was reading too high, so the tank was about 4 degrees cooler than I had it set at. Anyway, this InkBird 308 was the older style that had a direct hard wired probe instead of the “headphone jack” type. So, I got a replacement, which comes with the new connector that wires inside the InkBird, and swapped them out. Needed to unsolder the old probe and then solder in the new piece with the female connector on it to accept the new style probe. After doing all of this, the InkBird was still reading about 4 degrees off. So, I read the manual section about calibration and found out it is really just an offset setting that you can use to match the temp on the InkBird to the temp on another device, such as my digital thermometer. Now, the InkBird matches my thermometer exactly, and my tank is going to operate at the correct temp again.
Sorry for the long post, but I wanted to be as descriptive as possible.
P.S. I am pretty sure that every time you switch the unit from F to C, it returns all settings to default.