The drop core type automatically ejects the lead core by the gravity of the lead core. The rotary type conveys the lead core by rotation. The pulsating type (pressing type) conveys the lead core by pressing. The second pressing type (double-segment type, commonly known as double knocking), the first pressing the pen tip to extend the pen barrel, and the second pressing the lead core to extend.
The double-clamping type adopts a double-clamp structure, which shortens the distance between the clamp and the end of the pen tip, so that the remaining 8-15mm of residual lead in the mechanical pencil can be used to produce a whole lead without pressing. The core pushes it out, and you can write continuously. The automatic compensation type (automatic core output) does not require a rotating or pulsating device, and can automatically compensate the lead core and write continuously. The front flip type can directly press the nib to release the lead.