Limited Edition of 1972 Pieces. Hamilton Watch American Classic Chrono Matic 50 Limited Edition H51616731. Distinctive, daring and definitely an attention-grabber, the Count Down is based on the Chrono Matic E and limited to 1972 pieces. Powered by the H-31 automatic movement, at 48mm, its not for the faint hearted. The reverse panda dial is a signature Hamilton style statement. Bold red color accents underscore the dynamism of this multifunctional timekeeper which includes a countdown scale that gives the watch its name.