The HBLT26CM11 Twist-Lock Circuit Tester from Hubbell Marine offers an easy and safe means of evaluating a 125-volt AC shore-power receptacle. Plug the device into a 20A or 30A outlet and the colored LEDs will indicate whether the connection is correct or if there’s an unsafe circuit. Attached to the device is a two-sided plastic card to interpret the seven possible combinations of colored lights, including dangerous open grounds and reverse polarity conditions. A carabiner is included to clip the tester to a tool belt. $104.64; zoro.com
