Watchclock

The most commonly used form was the mechanical clock systems that required a key for manual punching of a number to a strip of paper inside with the time pre-printed on it.

Recently, electronic systems have increased in popularity due to their light weight, ease of use, and downloadable logging capabilities.

After the shift (or a specified time period, up to 96 hours in the case of the Detex Guardsman clocks), an authorized person (usually a supervisor), would unlock the watchclock and retrieve the disk or tape and insert a new one.

In the case of Detex brand clocks, each time the cover is opened or closed, a mechanical device would puncture the disk or tape at the current time; if a disk had more than two perforations on it, it proved that the clock had been opened and possibly tampered with, or records forged.

Inside buildings mounted near doors, were watchclock stations consisting of a small metal box with a hinged lid, which contained a numbered key affixed by a twelve-inch chain.