A small meter used in WW2. It only can do DC volt and resistance. No range knob but a separate socket for each range.
It is made by O.B.McClintock but because it was army gear it also has an other name. In this case: it was part of Test Set TS-26/TSM. The complete testset contains more stuff like a switchbox, testleads, and a wooden cabinet to mount all parts. Also needed are batteries, a groundrod and a clamp. A short description from the 72 (!!) pages thick service-manual:
Maintenance and lineman’s multirange voltohmmeter, to maintain common battery and magneto office equipment, and lines. Tests for grounds, crosses, shorts and opens, line capacitance to ground or to other lines, and distance to an open on a line. Voltage scale ranges 0-600VDC; resistance 0-1 megohm, or 0-10 megohms if 45V external test battery (BA-59) is used. Requires 1 internal 4,5V Battery (BA-31).
It is very smal. 14x9x6cm.
The resistors are peaces of art.
The battery for resistance measurement is mounted on the clamp you see on the picture above.