What is the difference between the material and shape characteristics of the needle and the needle

Millimeter needle and fire needle are two kinds of needles commonly used in TCM acupuncture treatment. Their differences in making materials and shape characteristics are as follows:
One, millimeter needle
Materials: Milliform needle is mainly made of stainless steel, but also other metals such as gold, silver, but expensive and rarely used clinically.
Shape features: The needle body is straight and smooth, the tip is round and not blunt, the needle body is smooth and uniform, and the needle handle is easy to hold. Its specifications are mainly distinguished by the diameter and length of the needle body, and the commonly used thickness is 2830 and the length is 12 inches.
Two, the needle
Materials: The needle is mainly made of tungsten wire or stainless steel, with high temperature resistance, not easy to deformation characteristics.
Shape characteristics: The needle body is thick round, sharp, needle handle is commonly made of tungsten alloy wire, high temperature resistant and not easy to fold. The length and thickness of the needle vary according to the treatment needs, and the commonly used needle is 3 to 4 inches long.