It will send out multiple alarms through sound and light. When voltage is detected, the tip emits a red light and beeps. The higher the sensed voltage or the closer it is to the voltage source, the higher the beep frequency. The screen displays red for high voltage and live wire detection, and green for low voltage and neutral wire detection.NON-CONTACT: Features an NCV inductive probe for AC voltage. Simply place the tip near a terminal strip, outlet, or supply cord. When the tip glows red and the pen beeps, voltage is present. The live wire detector automatically identifies live or neutral wires. Ideal for breakpoint testing and circuit testing for electricians and homeowners.DUAL RANGE: Detects standard and low voltage (12-1000V AC / 48-1000V AC) for versatile measurements. Press the S button to adjust sensitivity and select low range for use with doorbells, thermostats, irrigation wiring, etc. The NCV sensor automatically detects voltage and displays it on the bar graph.SECURITY LEVEL: IEC rated CAT III 1000V, CAT IV 600V. The electrical tester is double insulated for safety. High Voltage Alert warns of voltages above 90V; the screen turns red and the safety indicator illuminates.Material: ABS Color: As shown Package Contents: 1 x WT3010 dual range smart pen Only the above package content is included; other items are not included. Note: Light reflection and differences in display screens may cause slight variations in color appearance. Measurement error allowance is +/- 1-3 cm.