DMiotech Non Contact Voltage Tester Detector for Cars with Flashlight Alarm Beeper and Auto Shut-off AC 12V-1000V Voltage Pen Circuit Current Tester Wire Judgement DM8908C Safety. Made of high grade secure insulating plastic, with CE Marking and Double Insulated Symbol. There is nothing to worry about for the dangerous voltage detective work. Security level: CE CAT.III/CAT.IV 600V Wide Detection Range. From AC 12V to 1000V, almost cover all needed for the household. Every coin has two sides, the minimum voltage of working might too sensitive for some circumstances, which may annoy you. We apologize for that and need your understanding. This is not an issue of product defect, the pencil just goes beep while detecting 12V and above AC Voltage in an object.(Started work) Portable. Lightweight(0.1 LB), antiskid handle, stick cap for tying down in your jeans or pocket, cozy handy shape(6.14"x0.8"x0.8") and Built-in light(Especially useful in the darkness when blackout comes). All the details are meant to make the pen with more convenient and easy to be carried. Effective. Best in class smart chip, with the outstanding performance of non-contact voltage detection. Here is how it works: Press power button to start(Light on), moving the probe within 0.5" of the object. If there is zero AC voltage or below 12V, nothing happens. If it did detect alternating voltage, the higher AC voltage is the high frequency of alarm beeping and LED flashing. Energy Saving and Utility. Auto shut-down (The tester would power off automatically after 3 mins of no AC detected). Auto light off(Built-in light goes out in 5 mins whatsoever). This detector could help you with working in the junction box, finding dead bulbs, running wires for an outlet, distinguishing hot wire, etc. In some circumstances, an object could carry some fields<span class="a-text-bold"><u>when it was near by changing electric fields</u></span>(Maybe from a energized line or other things, )