The 002 is a particularly small propelling pencil which, according to collectors, dates from the 1920s and early 1930s and remained on sale into the middle of the 1950s. It was generally meant to accompany a notebook or pocket diary, slipping into the loop on the spine; hence the short length and the slim diameter.
The star on the cap top tells you which line it belongs to. An inlaid white star indicates the superior version, whereas a merely engraved star points to a pencil belonging with Montblanc's simpler third series. Both variants existed side by side, so an engraved star raises no question of authenticity; it simply reflects a different price bracket. On pencils of this age, the leads sold today often no longer fit, either in diameter or in length. Dealers specialising in historic writing instruments stock replacements; leads of the right thickness can occasionally also be cut to length at home.