This little cartridge adapter is an exciting new product for Platinum fountain pen users. It allows you to adapt International short ink cartridges so that they are compatible with Platinum fountain pens (which normally use exclusive Platinum fountain pen ink cartridges), thereby significantly expanding the variety of choices available for use with your Platinum fountain pen.
Works like advertised, it's an adapter for the smaller European ink cartridges.
I ended up not needing it but the ink cartridge included did come in handy. Just
wish I had realized it was a European cartridge adapter earlier XD