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Manufactured By Ber-Don Incorporating Clock indicating the time at which it is secured. Invented by A. Donovan 1921. This lock was used extensively between 1920 and 1950 for the purpose of securing the bag containing betting money that the on course bookies would have taken between races. It was the bookmakers responsibility to close the shackle just before the start of a race. This action stopped the clock and was proof for the race course officials that no bets had been taken once the race had commenced. The changeable combination was known only to the official who would open the lock during the duration of the race. The clock mechanism is shielded so that a magnet cannot be used to alter the timer.

I have seen this lock in different sizes.