GE developed a life-size dummy called the Copper Man to spare human volunteers of discomfort when testing the suit’s extremes. The dummy was 5 feet and 10 and a half inches tall, and covered with copper skin one-sixteenth inch thick. Its head, hands, torso and feet were connected by an electrical mesh that could take readings from 15 different body areas. 

The suit went into mass production in 1942 and pilots used it throughout World War II. The final design could keep flyers comfortable from plus 70 F to 60 F below zero.

Three GE Copper Men posing outside the U.S. Army Research Institute of Environmental Medicine in 1968.

GE advertisement explaining the postwar utility of the Copper Man in the April 1945 issue of Good Housekeeping magazine.