First of all, the lotion pump is 0.15cc, 0.2cc, 1.0cc, 2.0cc, 5.0cc, 10cc, an so on according to its pumping output;according to the diameter, it can be divided into 18mm, 20mm, 24mm, 28mm, 33mm, etc;According to the screw specifications, it can be divided into: 400, 405, 410, 415, 425, most of which are 410, the correct expression of the diameter plus screw specifications, such as: 28/410.