A 3x3x3 modification, which allows edges to be moved only into the shown direction. This means, that a layer can be turned in one direction, if the arrows of one or more edges point into the same direction. If they point into opposite direction, the layer cannot be turned at all.
If no arrow is shown on a face, the layer can be turned in both directions identical to a normal 3x3x3 Rubik's Cube.
After each quarter turn (90 degrees) you hear a click from the internal latches of the edges with arrows on it (if any in that move).
Size: 5.7cm standard edge length