If you have basic knowledge about multi meters you can try this small multi meter for basic continuity checks and voltage measurements. When testing DC voltage, AC voltage, DC current, resistance, diode, buzzer and battery, connect the red test lead to V 0 mA jack and black test lead to COM jack. When testing the current more than 200mA, connect the red test lead to OADC jack and black test lead to COM jack. When testing the temperature, connect the temperature probe to V 0 mA jack or COM jack. Please refer to the attached instruction manual for the operating instructions.