A British voice encryption device used with (for example) Larkspur radio system sets.
The authority for BID's was the Communications-Electronics Security Group (CESG) who were part of Government Communications Headquarters (GCHQ).
The BID/150 speech encryption key generator is a single channel device for use with the British Army C42 and C45 Larkspur radio system.
This was the first Combat Net secure speech system whose key was set through the use of punch cards within the device.
It was first used operationally by the 15th Signal Regiment during the Aden crisis in the late 1960s and was widely used from battalion level up to corps headquarters.