Connected nib / Pen

Generally the mechanical pencil's lead refills would be thrown away when it left about 1.5 centimeter. However, the lead refills at 1.5cm still can be use for a long time, so it is a wasted move to throw away these lead refills.

This design is to make a central tube at the head of the mechanical pencil, to become a connection between the new lead refills and the old ones, so that the lead refills can be use up until 2mm and below.