id hate to give it away…. This refill is compatible with brands such as : ACME, Aurora, Bexley, Delta, Diplomat, Faber Castell, Hauser, Inoxcrom, Itoya, Krone, Marlen, Montegrappa, Monteverde, Omas, Pelikan, Retro 51, Rotring, Stipula, Waterman and Visconti.”So, I feel fairly confidant that ANY of the G2/Euro refills listed should work for Waterman Carene and the Visconti Rembrandt.Some manufacturers might try to insist that you only use their refills but its bullocks. It’s insane. It inspired quick research on Fountain Pen Network which yielded excellent outcome!! I too would be keen to know if it works before I buy a tornado!You might need to trim the refill slightly with a sturdy pair of scissors or a knife but it should work. I disassembled them and found that there is is fiber pipe stuck into the back of the rollerball head.Does anyone know where I can buy some of these fiber/felt pipes. Once determined (multi-pen or regular refill), then the 0.5 and 0.7mm should be interchangeable. And these sellers on eBay want $3 per refill with $20 shipping. The issue is the length of the neck of the required refill, which seems a bit longer than your average Schmidt, Caran D’ache or Pilot.A good refill for Lamy Safari and Al-Star pens is the Jetstream refill. The Cross Gel inks are far superior and write much smoother than the MB Rollerball refills, last about 5-20 times as long (no ink dry-out) and are less than half the price online. !Searching for a Schmidt Rolling Silver 669 F replacement. Thanks!Twist at the metal cone just above the tip of the pen. Are all pens the same size, or how do you find out which one will fit your current pen? Can you help me?The zebra style of refils seem to be a family all of their own… I’m keen to get the F701 all metal zebra, but I hear their ink is inferior to many other pens. Like all Bic Round Stic. Are there any upscale pens out there that are fully compatible?Lamy Tipo (if you don’t mind the 207 refill tip extends out a bit).I love Monteverde Broad point ceramic gel refills for Parker style ballpoint pens. Hope that helps!Super comprehensive write-up. So.. if you had any advice on where to go or whether I am going about this problem all wrong, I would be so grateful :\ . Please drop me a line if it works and I’ll add it to the refill list.I’m a convert to really bold point gel pens I have a few nice Waterman ballpoint pens and would like to convert them to gel bold pens. !I have an Otis .925 hand made sterling silver rollerball pen that i recently rediscovered, but can’t find the refill for it. Now, if only I can find the SCHMIDT-MINE 628 DATA pen refill so I can have a stylus on my TRI pen. But not as smooth and great as the Pilot or uni =(I just bought another Zebra for the extra inks that come in the package. I appreciate it. I might pop over to my local pen shop and see if they have any of those pens or refills in stock so I can take a closer look this week.Ana, thanks for the feedback. Pilot G2, Pilot Juice, Schmidt 888 and the other rollerball & Pilot G2 refills listed in the article are shorter than Mont Blanc refills but are the same size in every other way but they do not have the threads. Just use scissors, a craft knife or blade to shorten the length to match the original length. Are you aware of anything else larger than Retro 51 that is compatible with the P8126 that has pretty good build quality? I mean that price could get them shipping to the moon!Mike, the zebra gel D1 refills are available through JetPens. I just forgot about the pen until I saw this article. I am a newbie when it comes to hacking refills. Thanks for the great pen info.I only found average performance from my Montblanc version of the Monteverde gel ballpoint refill, especially disliked the small amount of ink it contained.So I refilled an emptied one by using a drinking straw to ‘carry’ Pilot G2 gel ink with stopper fluid inserted into the refill.It worked, but a messy hack job to do on a regular basis.