Strict selection of raw materials We strictly select materials for production and processing, improve quality from the source, not easy to rust, corrosion resistance, higher hardness and more guaranteed 2. Fine workmanship Smooth and smooth surface, beautiful appearance and high practicability 3. Thread standard The thread is deep and standard, the force is uniform, the head is flat, the screw teeth are sharp, and it is not easy to slip during the rotation process, and the tightening effect is good