The mf8 Double Crazy Cube isn't your standard crazy 3x3. Each face has a double ring on it. On the red/orange faces, the inner circle remains stationary while turning. On the white/yellow faces, both rings move with the face. And on the green/blue faces, both rings remain stationary. This leads to very interesting solutions that are quite the challenge. Give it a shot if you think you've got what it takes!