Maker's Name: 
Master Instruments Pty Ltd
Where made: 
9.5 × 9.5 × 29.5 cm

This is an obsolete instrument, once used to measure the voltage of  a lead-acid cell under load. The prongs were applied to a cell of a vehicle battery, and the resistor across the prongs simulated the current load of an electric starter motor in a vehicle of the day. The voltage under load should be no less than 1.2 Volts, against an unloaded value of about 2.1 Volts.

Modern starters draw less current as they use a high-speed starter motor, which is geared down about 4:1 to provide the necessary torque to turn over the vehicle engine.