With most cartridge fountain pens it is usual that a reserve cartridge is carried as ink supply in the barrel; exceptions at Montblanc are only the Bohème series as well as the Mozart format. On the StarWalker the second cartridge should however not rattle; an enquiry at Montblanc in Hamburg confirmed that this is no standard behaviour. Anyone wishing to avoid the effect can simply remove the reserve cartridge. If the rattling occurs permanently, the writing instrument should be complained about at the specialist retailer.