Model GS-3 geiger counter produced by Nuclear Measurements Corp, Indianapolis, Indiana. "Manufacturer of the world's finest radiation instruments." Dial reads in counts / clicks per minute. 1955 - 1960. G-M tube is encased in rubber-tipped shield to provide the tube with maximum protection against shock. Dimensions: 3 1/4 in. x 6 1/2 in. x 7 1/2 in.