Thank you gentlemen!
If it is the same as the Y206P that W3PX points to they are used for "RG-59, RG-62, RG-140, RG-210 and RG-302 coaxial cables", none of which I am familiar with directly. Online chart says RG59, RG62and RG210 are 0.242" dia while RG58 is 0.195" dia. Also looks like RG8X is 0.242" dia, so maybe it will be useful to me in the future.
Now to look for a not-too-expensive crimper for it that will also do RG8/U (with different jaws) ...
Keith
N3KXZ