A container closure which indicates the number of times which a container is opened comprises a counting screw cap for a container three members arranged for rotation relative to one another, the first member threadedly engaging the neck of the container, the second member being arranged to be manually grasped for removing the cap from the container, there being provided a lost motion drive between the first and second members so that the second member is enabled to rotate through a predetermined angle in each direction without causing rotation of said first member while rotation of the second member beyond the predetermined angle causes rotation of the first member to screw the latter onto, or remove it from, the neck of the container. The third member carries indicating means and is interposed between the first and second members in such manner that it is driven by the second member during a substantial part of the lost motion rotation of the second member in one direction and restrained against motion by the first member during a substantial part of the lost motion rotation of the second member in the opposite direction. The indicating means cooperates with a series of numbers marked on one of first or second members.
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