Chemical pencil B4 plastic ribbed

The mechanical pencil is part of the B4 writing family. With a metal connector, it writes connected to the cap of the pen, in which there is a precise rotating mechanism for turning on (turning right) and off (turning left) the refill. The G2 refill (coin) is in a metal casing, which makes the mechanical pencil heavy enough to provide a good feel and balance compared to plastic pens.

We replace the cartridge by pulling the cap off the pen, unscrewing the mechanism, inserting a new cartridge (care must be taken with the spring), screwing the mechanism back in, and putting the cap back on the pen.