V-Cube 5 (5x5x5)
The V-Cubes are based on patents secured by Greek inventor, Panagiotis Verdes. The patents cover mechanisms for cubes ranging from 2x2x2 to 11x11x11 although products have only been released in the 5 - 7 range.
The V-Cube 5 is listed here separately from the professor's cube because it is a far superior product. It costs a bit more as a result. There isn't much of a speed difference for me between this and the Eastsheen 5x5x5 although the V-Cube 5 feels a little more robust.