Most Civil Defense Geiger Counters and ion-chamber survey meters were issued by the governmental Civil Defense organizations in several countries from the 1950s in the midst of the Cold War

Cold War

The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

 in an effort to help prepare citizens for a nuclear attack. Although often referred to as geiger counter

Geiger counter

A Geiger counter, also called a Geiger–Müller counter, is a type of particle detector that measures ionizing radiation. They detect the emission of nuclear radiation: alpha particles, beta particles or gamma rays. A Geiger counter detects radiation by ionization produced in a low-pressure gas in a...

s, most CD devices were ion-chamber radiological survey meters capable of measuring only high levels of radiation that would be present after a major nuclear event.
CD Counters came in a variety of different models, each with specific capabilities.