UNI-T UT11A is a voltage detector that can help you check for the presence of AC voltage in circuits or units. It features a voltage range of 50VAC to 600VAC and is Measurement Category IV 600V per IEC61010. The device is easy to use; place the detector tip on or near the circuit or unit to be tested, and the beep and flashing LED will indicate the presence of voltage. The UT11A also has a battery indication feature, which will let you know when the battery is running low.