1. Bidirectional indicating light: There is a bidirectional light emitting diode on the circuit board for polarity indication, red light indicates positive polarity green light indicates negative polarity. You can attach the alligator clamp either to negative or positive ground, while using the probe to touch the other side. 2. Clear Digital Display Readouts: automotive circuit tester with a clear LED digital backlit display for voltage readings, 0.1V resolution with ±0.2V accuracy gives you clearly visible digital readouts. Compared with LCD lights, this light tester is not affected by the brightness of light, so that be clearly read in daytime or dark areas. 3. Extended Spring Wire with Alligator Clip: Maximum extended to 110 inch long enough spring wire increases flexibility and a wide measuring area when testing, antibending design of the tail wire makes no worry about bad contact. Along with large size alligator clip for easy onehand operation. 4. Computer Save: This car fuse tester has a builtin circuit board chip, and more than traditional test lights. Equipped with insulation protective cover, it provides better grip and insulation protection. This circuit board with line protection function.