After nearly two years of development, the backpack carried, battery powered, voice radio receiver/transmitter known as the SCR- 300 was accepted in 1942. It was described in the War Department Technical Manual TM0-11-242 as primarily intended as a “walkie-talkie for foot combat troops,” giving it the nickname Walkie-Talkie. It was first used in action in the Pacific Theater. Special precautions were taken with assembly to prevent failure in the extreme heat and humidity. An anti-fungal coat of varnish was applied over the entire assembled circuit board, and the use of rubber grommets to seal the case sections effectively prevented moisture-induced damage to the radio’s electronic components. Motorola was to produce nearly 50,000 units during the course of the war.