Woodhead® Testers perform basic-verification and multi-function wire testing with compact, simple-to-use devices that are a must for any toolbox. Woodhead® testers are small devices with testing abilities that include reverse polarity, open-ground, open-neutral, open-hot, hot-and-ground-reversed, hot-on-neutral, hot-unwired, Ground Fault Circuit Interrupter (GFCI) functional and receptacle tension.