This entire product line has a very fragile plastic mechanism which soon breaks, after a few months of light use. The minor improvement in drawing quality is far outweighed by its very short lifespan. This applies to 0.3mm, 0.5mm and 0.7mm advancement mechanisms. The retractable mechanisms only last for a matter of weeks.

Using diamond hardened graphite "leads" with a fragile plastic advancement mechanism is an absolute joke!