a.k.a. Mind Twister
Patented by Y-J. Husn, 1993.
(plastic, 3.25 inches)
Each of six rotating discs has slots to hold eight numbers.
In the solved position, each disc has the numbers 1 to 8 of its color in clockwise numerical order,
except the white disc which has the number 1 to 7 in clockwise numerical order and one empty slot.
Where two discs are tangent and one of the discs has an empty slot at that position,
the number of the other disc at that position can be slid into the empty slot.
The object is to mix up the puzzle and then restore to the solved state.
presents a solution.
Here is a photo of the other side of the puzzle:
from: www.uspto.gov - patent no. 5,215,305