VINTAGE GERMAN HUNTERS HAND CARVED COO COO CLOCK. THE COO COO COMES OUT EVERY HOUR ON THE HALF HOUR. THE NUMBER OF COO COOS DEPEND ON THE TIME OF DAY. EVERY HALF HOUR, ONE COO COO, EVERY HOUR AGAIN DEPENDS ON THE TIME OF DAY.
Note, these clocks are sensitive to the environment. The back must be parallel to the wall, the weight on the pendulum has to be moved up or down to speed-up or slow-down the time. I suggest you watch a video to understand better.