D1 ≠ D1 3


Not everyone shares this opinion, not even everyone in my household, but I think gel refills are so much nicer than ballpoint refills. My holbein x Rotring 600 3 in 1 came with ballpoint refills, so it was a prime candidate for an upgrade: replacing the ballpoint refills with gel or hybrid refills. I had the idea after A.J. talked about the D1 refills in a comment on my video about this pen.

I started by consulting Ana’s refill guide to look for some nice refills.

It didn’t take long to pick some cool stuff for my order, not only refills, also a new pen (the Jetstream Edge in white). To get free postage with my order I also picked a few more refills with the intention of improving my wife’s Lamy 2000 multipen (the original Lamy ballpoint refills often skip when you start writing).

The two patients of this operation: Lamy 2000 and holbein x Rotring 600 3 in 1

What did I order? Jetstream refills, I like them based on my positive experience with them from the Hobonichi pens and from my Jetstream 4 in 1. I also got some Zebra refills. I haven’t used them myself but bought them before to go with a pen I gave someone as a gift.

When trying to fit the Zebra refills into the Lamy 2000 there was big disappointment. They didn’t fit. A quick look at the end revealed that the Lamy refills are slightly slimmer. Maybe D1 isn’t quite as standardised as I thought. I have to admit though that I don’t have much D1 experience as I generally prefer pencils and fountain pens.

A quick check with the callipers revealed that there are minute differences in the diameter. The Lamy M21 diameter is 2.32 mm, the Zebra JSB 0.5 diameter is 2.36 mm. 0.04 mm (0.0016 inches) difference. I also measured the Uni SXR-200-07 which turned out to have a diameter of 2.33 mm. Even though the Zebra didn’t fit the Lamy 2000 I managed to squeeze it into the Rotring 600. That left me with the uni for the Lamy 2000. The refill is only 0.01 mm wider but that was enough the turn a relaxing Sunday drive refill with butterflies (and the Loving You song in the background) into a heavy metal squeeze fest (with some Rammstein song playing from a broken stereo) with thoughts in my head that the Lamy 2000 will crumble under all the pressure. In the end it did, luckily, work. According to my own refill guide the D1 diameter is 2.35 mm. Who would have thought a fraction of a millimetre makes such a difference…

Since I talked about Holbein: Radio 4’s book of the week happens to be about him: The King’s Painter: The Life and Times and Hans Holbein.


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3 thoughts on “D1 ≠ D1

  • Ana

    I have squeezed the Zebra D-1 gel refills into my Lamy 2000 multipen. In fact, I’ve never used anything but the Zebra refills in it. I’m sorry they didn’t work for you.

  • memm Post author

    I was really scared I’d break it. I wonder whether either your Lamy has slightly bigger diameter or your Zebras had a smaller one. Since Lamy is updating the 2000 fountain pen every now and then (feed etc) my guess would be that your 2000 multiplem is slightly different.

  • Mike

    So true, I have faced the same with Fisher Universal Refill.

    I bought some Fisher Universal Refills and planed to use them with my Lamy 2000 multipen (which uses standard D1 refill). Unfortunately, it is not working.

    First, I broke them to the shortest position, which is around 67mm similar to D1 refill. Measured with caliper, the diameter of refill from Lamy is a bit narrower than Fisher refill. Lamy is 2.34mm (0.092″), while Fisher is 2.36mm (0.093″). It is a bit off from what Fisher claimed on their package(*). We need to apply certain amount of force to insert it into Lamy 2000. The worst thing is, since then my Lamy 2000 could not hold Lamy refill tight.

    After research, true D1 refill dimensions according to ISO 12757:
    – Length: 67(+0.3)mm, means the length is ranged from 67.0mm to 67.3mm
    – Diameter: 2.35(-0.05)mm, means the diameter is ranged from 2.30mm to 2.35mm
    (Product with dimensions out of range is not identified as D1 refill.)

    I have tested bunch of “D1 refills”, 2 groups of them were identified.

    Group 1, Confirmed to be standard D1 refill:
    – Schmidt (baseline, as they specified the compliance of ISO standard), Lamy, Parker, Rotring, Kaweco, Staedtler, Monteverde, Pilot, Uniball, Pantel, Platinum, Tombow and Ohto
    – Measured diameter: around 2.32mm to 2.34mm
    – Refills and pens of group 1 brands are perfectly interchangeable.

    Group 2, Questionable D1 refill:
    – Zebra, Fisher
    – Measured diameter: around 2.36mm to 2.4mm
    – Refills and pens of group 2 brands are perfectly interchangeable.

    During the test, I found that group 1 refills are loose fit inside group 2 pens, which could be used but fall out easily. On the other hand, after installed group 2 refills into group 1 pens, holding tube of group 1 pens were enlarged.

    The 0.01mm error would make huge difference. In pen enthusiastic community, Zebra’s multipen refill (4C) is well known that they are not D1 standard. It is because diameter of their refill is larger than 2.35mm, which is not complying the ISO 12757 specification: 2.35(-0.05)mm. They refill is not recommended to be used in other brands’ D1 compatible multipens, to avoid the what happened to my Lamy 2000 multipen. However, according to my test and some researches, it could be concluded that diameter of refills from Zebra and Fisher are similar.

    In short, Fisher Universal Refill is not D1 compatible refill.

    *Remarks:
    I have measured the diameter of Fisher Universal Refill with full length configuration as well.
    – Diameter of those two break off sections (a rod inserted to the end of refill body): 2.34mm (0.092″)
    – Diameter of refill body (end section with inserted rod): 2.36mm (0.093″)
    – Diameter of refill body (middle section without inserted rod): 2.34mm (0.092″)

    Since the rod with 2 breaking point is inserted to end of the refill as a plug. The section refill body with inserted rod is expended a tiny bit. This is the main reason towards the compatibility issue.