1COPPER MATERIAL: Made of premium copper material, these clips have good conductivity, and the surface is nickel plated, soft and does not damage the cable; The insulation sleeve makes it safer and more convenient to operate. 2STRONG SPRING: Each crocodile clamp has a sturdy and durable spring that is firmly clamped and will not deform after long term use. The crocodile clip works well in experiments, and prototypes. 34PCS: 4 kinds of crocodile pliers have different colors, which are easy to distinguish. The color coded cable allows you to test the circuit without crossover cable or causing a short circuit. Usually used as a micro fixture to bond parts together and weld cables together. 4WIDELY USED: They have a wide range of applications, suitable for use in homes, schools, and cars. They are often used in school physics laboratories to quickly and economically assemble circuits. More commonly used in manual welding devices, household welding tools, and electrical testing tools. 5FINE WORKMANSHIP: Well crafted with fine teeth and strong body, these crocodile clips are strong and strong in bite, not easy to deform, reliable for long term use.