This is an Ideal Industries 61-038 Stat Gard circuit tester, a type of electrical receptacle tester used to check the wiring conditions of 3-wire, 125V AC outlets. It helps identify common wiring faults like open ground, open neutral, reverse polarity, and more. The device uses indicator lights (visible at the bottom) to display the specific wiring condition. It is a plug-in device designed for fast and simple testing without the need for probes or meters. The product is specified for use with 125 volts and 0.6 watts. Disclaimer: Electrical testing should be performed with caution. If unsure about electrical work, consult a qualified electrician.