Micromark has this one for awg wire sizes #20-#30...
It's always in the top drawer of my own most oft-used tools, along with.....
It's 'big brother'....awg #10-#22...which I also have was obtained from the now-mostly-defunct Radio Shack eleventy-seventy years ago.....but commonly can yet be found in the tool departments of most big box home improvement stores and better hardware stores.
Reasonably priced.....simple in construction...easy to use...IMHO.
KD