Abstract: Apparatus for recording the opening or closing of a closure member, comprising a device for providing an electrical signal on opening or closing of the closure member or on actuation of an ancillary device associated with opening or closing of the closure member, an electronic circuit adapted to generate one of a number of unique codes on receipt of the electrical signal and to store the generated code, and a display device for displaying the generated code. In one form of the invention a reusable seal for a vehicle or container comprises a housing, and a cable secured at one end to the housing and releasably attached to the housing at the other end by a locking mechanism. Operation of the locking mechanism causes an electronic circuit in the housing to generate a random number, which is displayed by an LED display when a button is pressed. Any change in the number displayed indicates that the cable has been released. The seal can be used in the same way and can be repeatedly re-used.