Head size is exactly the middle value between medium and large sizes

Hello.

I want to buy a Ultracortex Mark IV, but my head size is exactly 58cm, so I am in doubt of the size.

From the site:
  Medium size: from 48 to 58 cm
  Large size: from 58 to 65cm

Would a medium be too tight ? Would a large be too loose ? Which one do you recommend me ? 

Thanks a lot.

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Send your question to contact at openbci.com
  • Hi Eduardo. I'm Aaron, the primary designer for the Mark IV.

    You are in luck in this case, since a wide variety of upgrades have recently been posted on the OpenBCI GitHub, including additional sizes mid-way between the others. You can find the STL in this folder: Medium-Large Ultracortex. That's in one piece, but it can be divided in Netfabb into however many pieces you'd like (or I could do it if you really need).

    If you're looking to have the frame printed, I'm sure we could work that out as well.


  • mark92630mark92630 Orange County, CA
    What is the range of head sizes for the "medium-large" Mark IV?

    TIA,

    Mark
  • Mark,
    The simple answer is about 53-62cm.

    An accurate answer is that range is approximate because peoples heads have different shape. The range is fairly forgiving though because there is 50% overlap between sizes. This means that if you have a perfectly average head, all three sizes would fit. Small adjusted all the way "out", Medium adjusted to the middle of its range, and Large adjusted all the way in. While the "range" depends on head shape, there is a specific head size/shape for each size headset. These are the exact numbers:

    Small (-10mm from Medium)
    48.9cm Circumference
    17.4cm Length
    13.5cm Width
    8.0cm Height (from circumference line)

    Medium-
    55.2cm
    19.3cm
    15.5cm Width
    9.0cm Height (from circumference line)

    Large (+10mm from Medium)
    61.5cm
    21.4cm
    17.5cm
    10.0cm Height (from circumference line)

    All five frame sizes are available from Shapeways Here.
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