The function of combination screws: It has perfect fastening capacity, is supporting high and low voltage contact, high and low voltage air conditioning wiring, is the electrical current and voltage, power, frequency, performance significantly improved compared with the traditional separation screws, can save people, labor, time and other advantages.

First, it depends on what requirements are there for the material of the screw, that is, the combination of screws that require the kind of data, such as stainless steel or iron.

Second, to see what is the demand for the national specification number of combination screws, common GB9074.8, GB9074.4, GB9074.13 and other specifications.

Third, it depends on the mechanical strength requirements of the combination screw, such as the grade is 4.8 or 8.8, and the screw needs to be hardened or not.

Finally, it should be noted that there are many types of combination screws, such as three combination screws, outer hexagonal combination screws, cross pan head combination screws, hexagonal combination screws, stainless steel combination screws, high-strength combination screws, such as iron combination screws are to be electroplated. Stainless steel combination screws are not required.