SAVE COST: Buy 1pcs Backlit Digital LCD Circuit Tester, also get 1pcs Voltage Continuity and Current Tester. Total 2 PCS different test lights. BIDIRECTIONAL VOLTAGE TESTING: Easy to attach the alligator clamp either to negative or positive ground, there is a light-emitting diode on the circuit board for polarity indication (Red light indicates positive polarity"+". Green light indicates negative polarity"-".) EASY TO READ: Our electric test pen has a large LCD digital display which is easy to read in both daylight and darkness because it has light. DURABLE ; FLEXIBLE: Design with a stretchable long cable and probe which makes it easy to get into those hard-to-diagnose areas. Anti-bending design of the tail wire, no need to worry about bad contact of the line. WIDELY APPLICATION: This circuit tester is ideal for checking various vehicles' electrical circuits, quickly checking automotive headlights, taillights, turn signal circuits, faulty sockets, and fuse connections, and also for testing other 6-24V DC wirings and circuits.