This is like a Rubik's cube in a way, as you must turn the inner cylinders to align the balls to the same color. It appears to be approx as difficult as the Rubik's cube - VERY difficult. It is one of Creative Crafthouse's only puzzles that we don't currently have a solution for. It does come solved, but mess it up and you're on your own.
Dimensions: 2.6" x 4"
Difficulty level: 4 (out of 6)
My high school students love it.