a.k.a. Turnstile, Twinspin, Engels Engima
Patented by D. A. Engel 1983, copyright GO Images Inc. 1986.
(plastic with cover, 4.75 by 6.4 by 1/2 inch;
the photos above show the puzzle on top of the cover)

The directions below are on the back of each puzzle; Jaap's Page presents solutions.



Further Reading
Jaap's Page, from: http://www.jaapsch.net/puzzles
Douglas Engels Solution Book, from: http://www.jaapsch.net/puzzles/circleman.htm
Engel Patent, from: www.uspto.gov - patent no. 4,415,158