The standard grinding of glass instruments is carried out in accordance with the national standard, which is also a common standard in the world. Common ones are: 10#, 14#, 19#, 24#, 29#, 34# and so on. Grinding mouth has a certain taper, which can generally be determined by measurement. Calipers are generally used, and the unit is millimeters. For details, please refer to/article/show-3.htm. When measuring, the inner diameter and the middle part should be measured.