Hank,
I had one for 10 meters and it worked as well as any
generic 1/4 wave, sort of. Not my first choice, but if
you need an unobtrusive antenna, it works, and it's
better than nothing. Don't know about the 20 meter one,
but the 10 meter Isotron was a real P.I.T.A. to tune.
'Doc

PS - The thing about 'snake oil', most of it contained
alcohol. Drink enough of it and who cares if it works
or not...