The Double 3x3 Cube is made with a black plastic core. The object of this puzzle is to scramble all of the colors and then organize them back to the starting position. This puzzle is extra tricky because it consists of two 3x3 cubes joined together in a row connected along an edge.
This mini version is substantially smaller than the original version.  An individual cube would measure 4.6 cm or 1.8 inches on the edges.  The smaller size makes it a little easier to hold in your hands.

• See at Puzzle Master