Review on Gardner Bender GCT-3304 Continuity Tester: Ensuring Electrical Connection in a Snap! by Brent Cole

Dead on Arrival. Also, the battery holder doesn't list polarity, so installing batteries is a 50/50 deal. Battery polarity information was not found on the device body, packaging, instructions, or website. Checking to see if the circuit has power and making sure there is no voltage could result in electrocution or worse. Spend a little more for something safe and secure.