It would be unfortunate to see a beautiful pen damaged or dissolved by cleaning with the wrong supplies (especially since you mentioned that your friend was a "clean-freak". The Lamy M22 mini ballpoint refill has a unique size and shape that will only fit some Lamy ballpoint pens and one pen from LOCLEN.

The Waterman ballpoint refill has a unique size and shape, and it will only fit their ballpoint pens. These are metal or plastic body stick refills for retractable pens with a slim tip and spring shoulder (wing, crimp, pinch) that is 33.This gift set from Nina Ricci features a well balanced polished chrome and grey ballpoint pen and an 8cm by 11cm (when folded) black leather card holder with grey interior. Refills that match the ISO X20 large capacity ballpoint standard are metal or plastic body refills for retractable or non-retractable pens. The Fisher Pressurized Contractor Tool ballpoint refill is a unique refill to fit the Fisher Contractor Tool. It has a similar profile to the Fisher Space Pen compatible refills, so it will fit in some other pens of that profile. The Waterman Titan / Titane CF is a proprietary length and shape refill that will only fit older Waterman ballpoint pens.

The Sheaffer Skrip is a proprietary length and shape refill that will only fit older Sheaffer ballpoint pens. The Caran d’Ache Frosty 828 ballpoint refill will only fit their Frosty and Infinite ballpoint pens.Refills that match the ISO X20 ballpoint standard are available from numerous pen and refill makers.