The MM39 is an auto-ranging multimeter with a large rotary switch for easy selection of the required test,
even when wearing gloves. There are two test buttons, one to lock the range and the other to hold the results which are displayed on a 3½ digit LCD screen.
The main test functions are AC voltage and DC voltage and current and resistance. The MM39 measures both AC and DC voltage between 0.1mV to 600V and AC and DC current between 10mA to 10A. There is a diode test and an audible continuity test which sounds at less than 25Ω.