Protection design: Equipped with reverse polarity protection to prevent damage caused by incorrect battery installation Includes 5V, 9V, 12V and 24V. This feature allows for a variety of applications in different electronic setups. Adjustable voltage resistor: By rotating the voltage resistor clockwise, the user can easily adjust the device for use with various power sources Suitable for use in environments with temperatures from -10 to +65°C and humidity from 10% to 80%. Although the meter not burn out, it not display a reading until the polarity is corrected, thus increasing the durability and usability of the device., Manufacturer: Akfldms