The IDEAL Electrical 61-051 E-Z Check Plus Circuit Tester has a no-slip ergonomic design that maximizes comfort. The premium neon lamps prevents readings; it has a tough, impact-resistant case. It Tests for correct wiring, open ground, reverse polarity open hot, open neutral, hot on neutral, hot and ground reversed with open hot and ground fault interruption in 3-wire 125-Volt AC circuits. It also tests GFI receptacles for proper operation.