a.k.a. Hockey Puck Puzzle
Patented by Z. Pataki, U. Mszmp, and . Csomos 1991, purchased from PuckPuzzles.com 2007.
(plastic, 2.9 inches diameter by 1 inch thick)
The outer ring can rotate around the center,
and there is an axis along which two halves of the puzzle can be flipped with respect to each other.
This puzzle is different,
but in the theme of
The puzzle can be easier depending on the graphics used;
below are some other examples.
presents a general solution,
and notes that this puzzle mechanism is virtually identical to the earlier
from: www.uspto.gov - patent no. WO9,102,574