With a car installed radio, the officer cannot communicate to the station when out of the car. To improve mobility, handheld radio communication devices were developed. At first they were big and expensive, used by the military in the Second World War.
Galvin Manufacturing Corporation (later Motorola) created the Handie-Talkie. The first equipment to be called Walkie-Talkie was a 15 kilogram back pack unit. It took until 1962 before Motorola introduced the 33-ounce "brick" walkie-talkie. The walkie-talkie is known for its Push To Talk (PTT) button.