A pencil has the disadvantage that its length continues to decrease with increasing use. When working on high-quality drawings, it thus becomes increasingly difficult to achieve a good quality result as the pencil can no longer be held properly.
FABER-CASTELL had already solved this problem in the 40's with the introduction of the so-called TK clutch pencils, which used leads of a similar thickness to conventional wood-cased pencils.
(Incidentally, the TK trademark registered by FABER-CASTELL represents the German initials for the main user groups of technicians [Techniker] and artists [Künstler].)