The Clock is a two-sided puzzle showing nine clock-like images on each side. The aim of the puzzle is to set all nine clocks to 12 o'clock (straight up) on both sides of the puzzle.
There are four wheels, one at each corner of the puzzle, each allowing the corresponding corner clock to be rotated directly. The corner clocks, unlike the other clocks, turn on both sides simultaneously.
There are also four pins located between the clocks which span both sides of the puzzle. The state of each Pin (in or out) determines whether the adjacent corner clock turns together with the three other adjacent clocks on the front side or on the back side: thus the configuration of the pins determines which sets of clocks can be turned simultaneously by rotating a suitable wheel.
