Magician shows a handsome clear plastic rod with six different colored gems on it. There are also six different color gems on the opposite side of the rod.
The spectator selects one of the different colors and INSTANTLY all the gems change to selected color on BOTH SIDES!
This Hot Rod is approximately 4″ long.

Also includes an instructional 32 page booklet:

40 Tricks with a Hot Rod and Other Color Change Rods by Scott K. Anderson