I am looking for information on an exercise device from the 1970s that
none of my friends remember.

I used this "exercise machine" at the El Caribe beach club in
Brooklyn, New York.  You would exercise your glutius muscle by sitting
on the machine while it spun, and it would vibrate and somehow improve
the tone of your muscle.

The machine was shaped like a large barrel on its side, and the barrel
would spin around.  On either end of the barrel were stabilizing
handles that you would hold as the barrel spun underneath you.  The
barrel was made of slats of wood (with an inch of space between each
slat).  I remember that the slats were textured rods (as opposed to
bars).

I am looking for an article (with picture) describing this "fad", and
of course would be interested in purchasing one as a gag!

Thanks