Yin Yang

Yin Yang - Ton Onosaka

Ton Onosaka provides us with this interesting looking effect; that is fun to perform. 

Even better, this effect features two routines, one for a single spectator and another featuring a two-spectator version.

Effect: The performer shows a number of cardboard rings.
On one side each shows a dozen ESP symbols, half black-on-white, and half white-on-black.
The other side is similarly divided half black and half white, with radial lines corresponding to the centers of the symbols.
It is pointed out that each ring features a different layout of symbols.
One ring is taken, and cut in half using a pair of scissors.
The performer and spectator each take a half, and each uses the scissors to cut the half-ring along any of the printed lines.
The performer cuts his half-ring first, so there is no way he could know where the spectator's half-ring would be cut.
Never-the-less, when the pieces are turned over, it is seen that both performer and spectator have cut through exactly the same symbol!

Variations are also possible, including one in which spectators do the cutting on "both" half-rings, and still the symbols match!
Can you repeated 12 times before refills are needed, or can be altered for even more performances.

Instructions by Phil Goldstein.