?PRECISE READOUTS CLEAR DIGITAL DISPLAY?Bright LED display shows highly clear readings in any lighting condition, 0.1V resolution gives you reliable indication and shows you the voltage number easily quickly. Bidirectional light emitting diode on the circuit board for easy battery load testing, red light indicates positive polarity, green light indicates negative polarity. ?QUICK DETECTION EXTENSIVE USE?WINAMOO auto circuit tester helps you to quickly test car battery voltage and diagnoses issues in 3V-48V systems, including alternator tester functionality of car/truck/SUV/boat charging systems. Also to inspect circuit tester integrity of headlights, taillights, turn signal circuits, faulty sockets, fuse connections and more. ?SHARP PROBE ANTI-LOST PROTECTIVE SLEEVE?Sharp stainless steel probe for piercing insulation with ease, also for hard to reach tight areas. Integrated anti-lost protective sleeve to secure the probe during storage and safeguarding against damage, making sure no stab and wound and won't be lost wherever you go. ?EXTENDED SPRING WIRE LARGE ALLIGATOR CLIP?High quality 96 inch long enough spring wire increases flexibility to access across broad areas when testing. Attaching with large crocodile clip for easy single-handed operation, which is boosting the efficiency for car battery capacity checks and beyond. ?ULTRA-DURABLE SAFE CONSTRUCTION?This voltage tester pen adopts ergonomic handle for comfort and safe grip. Constructed with premium ABS body with higher transparency, shatter-proof and durable. Ensuring reliable battery meter and circuit analysis for safe operation, making them an essential tool in electrical troubleshooting.