GearWrench 129D - 6 V/12 V Low Voltage Circuit Tester Quickly and reliably test for the presence of voltage with the GEARWRENCH 129D 12-volt circuit tester, a durable and essential tool for automotive and electrical diagnostics. Designed for fast, accurate results, this handheld tester detects both high and low voltage conditions in 12-volt systems, making it ideal for checking ignition spark, battery circuits, fuses, switches, and wiring. Simply connect the alligator clip to a ground source and probe the circuit?the integrated bulb illuminates when voltage is present, providing immediate visual confirmation of electrical activity. It?s especially useful for verifying spark plug operation and diagnosing open or broken circuits in vehicles, lawn equipment, and other small engines. Constructed with a rugged plastic housing, the 129D is built to withstand the demands of daily use in garages, workshops, and job sites. Its compact design measures 5 inches in height, 1-13/16 inches in width, and 1 inch in length, making it easy to store and handle in tight spaces. The multicolored body enhances visibility in toolboxes and helps prevent misplacement. Weighing only 0.290 pounds, it?s lightweight and portable for convenient use across multiple workstations. The integrated test lead with a durable alligator clip ensures a secure ground connection, while the sharp probe tip easily penetrates insulation or contacts terminals without damage. Packaged on a card for retail display and easy storage, this circuit tester is a practical addition to any technician?s toolkit. Whether you're a professional mechanic or a DIY enthusiast, the GEARWRENCH 129D delivers dependable performance, straightforward operation, and long-lasting durability for everyday electrical troubleshooting. Features - 12-volt circuit tester for fast detection of high and low voltage conditions - Built-in bulb illuminates when voltage is present for instant visual feedback - Ideal for testing spark plugs, ignition systems, fuses, switches, and wiring - Alligator clip lead provides secure grounding during testing - Sharp probe tip allows easy access to terminals and connectors - Compact and lightweight design for portability and ease of use - Durable plastic construction resists impact and wear - Multicolored housing for high visibility and quick identification - Perfect for automotive, marine, and small engine electrical diagnostics - Individually carded for convenient packaging and storage Specifications - Brand Name: GEARWRENCH - Model Name: GEARWRENCH 129D - Part Number: 129D - UPC: 082171001291 - Global Trade Identification Number: Not specified - Product Type: Circuit Tester - Voltage Rating: 12 V - Material: Plastic - Color: Multicolored - Length: 1 in - Width: 1-13/16 in - Height: 5 in - Item Weight: 0.290 lb - Packaging Type: Carded - Number of Items: 1 - Manufacturer: GEARWRENCH Product Application The GEARWRENCH 129D 12-volt circuit tester is engineered for fast, reliable diagnostics in automotive and electrical repair environments. It enables users to quickly verify the presence of voltage in ignition systems, battery circuits, and control modules, helping to isolate faults and reduce troubleshooting time. Commonly used to check for spark at spark plugs, it is an essential tool for diagnosing no-start conditions and ignition failures. Its simple, no-battery design ensures consistent operation without the need for calibration or charging. With rugged construction and intuitive functionality, the 129D is a trusted choice for mechanics, technicians, and DIYers who require a dependable, easy-to-use voltage tester for everyday electrical system checks.