Your Go-to Power Screwdriver SKIL's Circuit Sensor Technology is a patented innovation that detects live wires in outlets, switches, cords, and fixtures from up to one inch away. Simply hold the cordless screwdriver near the source of electricity and press the detection button. If the circuit is live, the red light illuminates and an alert sounds. With this feature, you'll always know where live circuits are located before getting started on your project.