Clearly detects 100-500 volts AC without metal contact Tip glows red when voltage is detected Pocket size for handy use anywhere Two year guarantee Any voltage over 25 volts AC is regarded as hazardous. Kewstick detects voltage from 100-600 volts AC so care must be taken at all times. For correct & safe operation hold the unit by the main body & avoid placing your fingers beyond the finger guard. Always check Kewstick on a known live source 200 volts AC before & after each work session.