KLEIN TOOLS ET40 is an electronic ac/dc voltage tester. It features indicators for positive and negative dc polarity, and tests DC voltages as low as 1.5 V. It tests AC voltages 12 to 240 VAC. Excellent for checking, verifying or troubleshooting common residential electrical wiring in electrical outlets, light fixtures, doorbells and more. It operates on 2 x AAA batteries.