Nuts are fasteners with internal threads that are used in conjunction with bolts, and mechanical parts with internal threads that are used in conjunction with screws to transmit motion or power.

Nuts are nuts, parts that are screwed together with bolts or screws to provide a fastening effect. They are a necessary component for all production and manufacturing machinery. There are various types of nuts, including national, British, American, and Japanese standards. Nuts are classified into several types based on their materials, including carbon steel, high-strength, stainless steel, plastic steel, etc. According to product properties, they can be classified into ordinary, non-standard, (old) national, new national, American, British, and German standards. Due to differences in size, threads can be divided into different specifications. Generally, Chinese and German standards use M to represent (such as M8, M16), while American and British standards use fractions or # to represent specifications (such as 8 #, 10 #, 1/4, 3/8). Fasteners are parts that tightly connect mechanical equipment. They can only be connected together through the inner thread, nuts of the same specification, and screws. For example, M4-0.7 nuts can only be paired with M4-0.7 screws (in nuts, M4 refers to the inner diameter of the nut being about 4mm, and 0.7 refers to the distance between two threaded teeth being 0.7mm); The same applies to American products, for example, a 1/4-20 nut can only be paired with a 1/4-20 screw (1/4 refers to a nut with an inner diameter of approximately 0.25 inches, and 20 refers to 20 teeth per inch)