Solitaire writing instruments bear serial numbers of two letters and six digits; on particularly high-quality solid-gold pieces it is partly only five digits. With the typeface, Montblanc changed around the year 2000 from round to angular, laser-engraved digits. The designation 'Pix' was originally the name for the mechanical pencils of the 1930s and has been engraved since about the early 2000s also on other writing instruments as well as on watch models (e.g. of the Summit range); older models that expired before the introduction of this practice, like the 146 Bordeaux, therefore lack the inscription.