They have the ability to detect intensity of IR rays and test for live wires
These multimeters can measure AC/DC Voltage, AC/DC Current, resistance, capacitance, frequency, temperature (only 603A+), hFe, diode and continuity. The unique feature is that these can test for IR rays being emitted and help in knowing their intensity. For example, the intensity of IR rays from TV remotes can be tested to infer whether the batteries have to be changed or not. These can also test for live wires. Data hold function allows user to hold the measured value for logging purposes and auto power-off helps in conserving and prolonging battery life.