Features: More sensitive needle, better effect. Metal clip can clamp the body metal and screws well. Spring wire sleeve protector, anti broken line protector, make the thread more durable. The clip connected to the nagative pole, the pen tip tests the positive pole, and the bulb and display light up. The clip connected to the positive pole, the pen tip used to test the negative pole, and the display not lit only light on. Specifications: Material: Plastics Size: Package: Approx. 28x10.5x4cm/11.02x4.13x1.57in Measuring Pencil: 19x0.5cm/7.48x0.20in Type: A/B/C Note: Measuring range: 6V/12V/24V, do NOT use beyond the measuring range. Please notice that the 3 types circuit tester pen has differences, type A does NOT have LED digital display, while type B and C has digital display, the wire of type B has spring cable, but the wire of type C has common wire. Positive and negative pole distinction: The clamp clamped to the positive pen to measure the negative pole light green(negative pole line), on the contrary. the clamp clamped to the negative pen to measure the positive pole light red(positive pole line). Package includes: A: 1x Tester(NO LED Digital Display, Common Wire) B: 1x Tester(LED Digital Display, Spring Cable) C: 1x Tester(LED Digital Display, Common Wire)