The only Rotring fountain pen I have, a Core, uses short or long international cartridges or a standard international converter; Parker carts or converters won't work in it. I can't help you with the ballpoints.
all of the above is true enough. but Waterman did have some waterman lady converters for $25 each that fit the CF pens. Dont know if they still do or not but did 2 years ago.
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Tu ne cede malis sed contra audentior ito ~Yield not to misfortunes, but advance all the more boldly against them
Thats what they wanted to charge me. They have a monopoly on them. try finding one somewhere else. Only other option is find a box of old cartridges in the bay & do the syringe refill trick. I have some extra, blunted syringes if anyone needs some.
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Tu ne cede malis sed contra audentior ito ~Yield not to misfortunes, but advance all the more boldly against them