it will send out an audible and visual alarm when the AC voltage is detected. It can help you recognize zero wire and live wire safely and easily. [Backlight LCD Screen Flashlight] Clear LCD screen with backlight greatly enhances the reading experience and makes it easy to read. Flashlight to illuminate the measurement object without fear of dark environment. [Battery Operated Compact Size] Powered by 2 AAA batteries, auto shutdown in about 15min to save power. Ergonomic design, perfectly fits your palm for convenient use. Concise appearance, small and lightweight, easy to carry. Note: 1. Please read the user manual carefully before use. 2. Size and color may be slightly different due to manual measurement and different light conditions. Thanks for understanding. Specifications: Model: HT124A/ HT124B (Optional) --HT124A: without Capacitance Measurement/ Diode Test --HT124B: with Capacitance Measurement/ Diode Test Color: Black Material: ABS Screen: LCD with Backlight Max. Count: 4000 Counts Max. Voltage: 600V DC or AC Max. Resistance: 40M Continuity: #xff1c;Approx. 50, buzzer will sound and the indicator light will be on Max. Frequency: 4MHz Max. Capacitance: 4mF (HT124B only) Display Diode Voltage Drop: (HT124B only) Power Supply: 2 * 1.5V AAA Battery (NOT included) Auto Shutdown: about 15min Operating Height: #xff1c;2000m Operating Environment: 0~40 ( #xff1c;80% RH, #xff1c;10 non condensing) Storage Environment: -10~60 ( #xff1c;70% RH, remove the battery) Item Size: 125 * 65 * 20mm / 4.92 * 2.56 * 0.79in Item Weight: 104g / 3.66oz Package Size: 16.5 * 9.5 * 5cm / 6.50 * 3.74 * 1.97in Package Weight: 228g / 8.02oz Package List: 1 * Smart Digital Multimeter 2 * Measuring Pen 1 * User Manual (English)