Patented by Erno Rubik, 1983.
(plastic, 2.5 inches diameter by 1.5 inches high;
yellow opposite green, blue opposite orange, grey opposite red;
also made in promotion versions and with six distinct pairings of the six colors;
originally packaged like a cheese, with directions on the package bottom)

A predecessor to the Rubik UFO where the two layers cannot rotate with respect to each other. Similar to a Puck Puzzle with fewer sections and without the center portion (but with the ability to flip along any of the three lines). Although this is not a trivial puzzle (harder than Rubik 1x2x2), it is not hard to solve by just playing with it. It can be solved to different color combinations (e.g., left below) and different patterns (e.g., the two on the right below). Jaap's Page presents a solution.



Further Reading
Jaap's Page, from: http://www.jaapsch.net/puzzles/kepkorong.htm
Rubik Patent, from: www.uspto.gov - patent no. 4,410,179