After some additional Google research, I found them. Made by
Fair-
Rite Products Corp. PN is probably: 2643806402. Product
description matches unit on hand, and lists it as type 43 material
with a Z around where I want to operate of about 20 ohms.

My guess is that you got the 20 ohms (for an unstated intended
frequency of use) by extrapolation of the published data from 10 to
250MHz. You probably also read that the core material is recommended
for 25 to 300MHz. Both of these would suggest that the material is not
the best for your intended frequency, whatever that is.

So, for an effective choke, you may need 25 to 50 of these things.
They are only a half inch long each, so that is just 13 to 25 inches
in length in total, not unusual for that type of choke.



Actually, since I probably will be using RG8X I can most likely
loop a couple turns through each bead... which should preclude the need
for quite as many.


Ed