1. Head refers to the Internet per square inch of screen space the number of eyes, 50 head per square inch refers to the hole are on 50, 500 head is 500, the higher the mesh, the more hole. Except that the hole screen, it can express at the same time for the particles through the screen size, the higher the mesh, the smaller the particle size.

2. Powders particle size, said particle size. Because of the complexity of particle shape, usually have screen size, the settlement size, the volume equivalent particle size, surface area of equivalent size, such as express several methods. Screening is the particle size through the sieve mesh size to 1 inch (25.4mm) width of the sieve mesh numbers, so called "mesh." At present, there is at home and abroad that have not yet unified technical standards for powder particle size, all businesses have their own definition of target size and method. In different countries, different industries have different specifications of the screen criteria, and therefore "eye," meaning it will be difficult reunification.

he following table is usually for domestic use and the screen mesh size (μm) table.