When measuring the length, 7 mm is generally expressed as 0.7 cm, which is a moderately small size. If measured in millimeters, it is generally used in building materials or decoration industries to describe some relatively small things, such as doors and windows, glass, tiles and so on.

In addition, in the jewelry industry, "7mm" is also used to represent the size of jewelry, such as 7mm pearl necklaces and so on. In addition to the construction, decoration and jewelry industries, the size of 7 mm can also be used in other fields, such as manufacturing electronic products and medical devices. In these fields, the dimension of 7 mm is usually used to describe the size and spacing of parts to ensure the quality and reliability of products.