This high-quality auto circuit tester is a versatile tool that allows you to test circuits from 6V to 24V with ease. The built-in light bulb provides clear visibility into your car's electrical system, while the sharp steel probe ensures accurate measurements. Ideal for checking circuits, fuses, switches, and wiring in various low-voltage systems including cars, trailers, boats, motorcycles, and more. Simply clamp the alligator clip to the ground wire, measure the contact with the pen tip, and let the light bulb indicate the circuit's status. Made of durable ABS and metal materials, this tester offers a clamp capacity of 20A and features a 3-watt replaceable bulb. With a voltage test range of 6V to 24V, this pen tester is a must-have for any DIY auto enthusiast.