1.[3-72 V Wide Testing Range] This professional automotive circuit tester light with 3-72V DC voltage testing range, widely and ideal for checking various vehicles¡ electrical circuits, automotive headlights, taillights, turn signal circuits, faulty sockets, fuse connections, also for testing other 3-72v DC wirings and circuits. 2.[Buzzing Bidirectional Voltage Testing Mode] You can attach the alligator clamp either to negative or positive ground, there are two light emitting diode on the circuit board for polarity indication, red light indicates positive polarity and green light indicates negative polarity, and one sound buzzing for positive and double sound for negative. 3.[Computer Safe Accurate LED Digital Reading] Digital LED voltage display for accurate volt readouts, .1 v resolution ratio with high accuracy. Compared with LCD, clear&visible LED reading display for day and night. LED circuits board with micro current than traditional test lights, more secure and burn-resistant to automotive computer board. 4.[Quality Made & Anti-lost Needle Cover ] Sharp stainless steel probe for piercing wires, also for hard to reach tight areas. Heavy duty test light body constructed with high quality plastic, shatter-proof, more durable than normal test lights. Anti-lost Silica Gel Needle Cover was designed as a part of the spring wire, no worry about losing it during testing and storage.