UT139A/B/C DMM is a small auto range, hand-held 3 1/2—3 5/6 bit true RMS multimeter featuring complete function, novel structure, high reliability and safety as well as large screen for display . It can be used for measuring AC/DC voltage and current, variable frequency voltage (V.F.C), resistance, diode, circuit on-off, capacitance, frequency ratio, NCV non-contact AC voltage sensing and so on, is an ideal portable maintenance instrument for users.