The use of red semiconductor laser can achieve a detection distance of up to 3m. The ultra small size is only W8.1 × H23.2 × D11.8. Equipped with sensitivity adjustment knob and action indicator light. A high-precision detection system that can detect small objects and small color differences. Small objects, high-precision positioning detection, capable of detecting metal wires with a minimum φ 0.01mm. With short-circuit protection and power polarity protection. High response speed, action reset time is only 0.25ms. Excellent anti-interference function can be installed tightly in two sets.