hac5x3,
Here's the description of the rating system:
https://en.wikibooks.org/wiki/Unite...y_and_valuesThis is probably the most complete catalog of meter types you will find. Additions are still being made. I've added a few minor variations myself.
The "rarity" index is based on a 27 year-old survey of Meter Stamp Society Members. It was a small group then and even smaller now. I would take the "rarity" factor listed with a BIG grain of salt. The survey sample was small and the market for meters is very thin. With some notable exceptions, most meters are inexpensive. Most can be had for a few dollars. If you can find them for sale.
I think meters are fun an interesting to collect. But this is a very minority opinion. If you like meters, consider joining our group!
https://www.meterstampsociety.com/Dan

Dan