Não consigo ver a foto.
De qualquer forma, aqui ficam algumas informações:
"Cartridges come in different sizes. Some pen manufacturers, including Aurora, Lamy, Parker and Sheaffer, use proprietary cartridge sizes. Others, including Caran d'Ache, Conway Stewart, Montblanc, Pelikan, Rotring, Yard-o-Led, more recent Waterman pens and most cheap unbranded European and Chinese pens, use the international cartridge size.
The international cartridge is not a specific documented standard. Nor does it have an agreed-upon name — it is also called European (usually by American pen manufacturers), Standard and Universal. There are two sizes of international cartridge, sometimes called short (38mm in length) and long (72mm in length). Some pens will take both long and short cartridges, and some will only take short cartridges. Some pens are also designed to accept a spare second short cartridge stored in the barrel.
The international format is also used by many specialist ink manufacturers, including J. Herbin, Private Reserve and Diamine, for some of their more popular colours. Although this increases the amount of choice available to cartridge pen users somewhat, it still does not match the variety available in bottled form.
Note that Waterman long cartridges, which are sold as "Large Size Standard Cartridges", will not work in many non-Waterman pens; non-Waterman large international cartridges will, however, work in modern Waterman pens.
Using an incorrectly sized cartridge (for example, attempting to use an international cartridge in a Parker) can lead to leaks. In some cases it can also lead to the pen being damaged. Most manufacturers will not honour a warranty claim if the damage has been caused by using the wrong type of cartridge."
Tens aqui também um guia visual:
http://www.refillfinder.com/catalog/refill-size-guide.html
Por último, tirei duas fotos a um Parker e um Internacional para comparares. Poderá ainda ser um formato diferente, compatível com a Lamy, etc...
(https://www.mediafire.com/convkey/65eb/fn6w14dyhprdesu4g.jpg)
A da esquerda, maior, é Parker e o da direita é internacional. O diâmetro exterior do encaixe da Parker é 5.25mm, o do internacional é 4.30mm.
Tens aqui também os mesmos vistos de cima; o da esquerda é Parker, o da direita internacional, e aquilo é uma mola de roupa... ;D
(https://www.mediafire.com/convkey/1813/t3srpjwrriefsha4g.jpg)
Espero que ajude.