The Klein Tools Electronic AC/DC Voltage Tester, No. ET40, identifies and distinguishes between AC or DC voltage. This product tests AC voltages from 12V to 240V, and DC voltages from 1.5V to 17-24V. The tool indicates polarity when measuring DC voltages, and features built in test lead holders on the sides of the tester. The tool powers off automatically after two minutes of non-use to conserve battery life.