The INNOVA 3420 Smart Test Light/Circuit Tester by Equus Products Inc. checks voltage and ground on electronic systems, including wiring, fuses, batteries, cables, sensors, switches and more. Its unique transparent handle uses LEDs to identify connections by color: white = good connection, red = voltage detected and green = ground detected. The light connects to a vehicle cigarette lighter/power plug receptacle and sturdy, detachable twin alligator clamps. It also features an ergonomic grip and 6' leads for long-reach connections.