Sears Tower Model 6157 GM Meter (ca. 1954-1960)
This GM survey meter was manufactured for the Sears Roebuck Company by El-Tronics Inc. of Philadelphia. A very similar instrument was sold under the El-Tronics name as the Model PR-5. The latter was described in the Atomic Energy Commission Instrument Catalog (RIB-8) as follows: "Portable beta gamma count rate meter with long life geiger tube designed for field survey work in location of radioactive ores and operating entirely from two flashlight batteries."
The above photo shows the GM probe on the left side of the case, this would usually indicate that the individual using it was left handed.
Detector: GM tube, 30 mg/cm2 wall
Range: 0-0.2, 0-2.0 and 0-20 mR/hr
Size: ca. 4" x 8" x 4"
Weight: ca. 5.5 lbs.
Output: No speaker, but it has a phone jack and a small light that flashes according to the count rate
Batteries: Two 1 1/2 volt
Atomic Energy Commission. AEC Radiation Measuring Instruments, RIB-8 (supplement 2) July 1, 1954, page SGM-111A.