Multi-function DMM Protek's multi-function DMMs No. 6100 and 6300 are auto-ranging and 4,000-count, with 3 3/4 digit display. In addition to measuring AC/DC voltages and AC/DC current and resistance, the models also offer duty cycle, frequency, capacitance, diode check and transistor test capabilities. 'Smart Jack' units light up to indicate appropriate input, and overload protection fuses may be reset without opening the meter case. Relative mode, data hold and sleep mode add to the functional ease.