C.S. Osborne makes some large needles. For example:
STRAIGHT SINGLE ROUND POINT NEEDLE – HEAVY #554.
Lengths are from 6 inch to 24 inch, with varying diameters.
The 25 inch needle is a gauge 11, which is 2.95 mm diameter.
Here’s a website.
“osborneleathertools.com/product/straight-single-round-point-needle-heavy/”
Osborne uses the “British Standard Wire Gauge”.
Maybe the upholstery needle supplier you reference does also.
Refer to this Wikipedia article.
“en.wikipedia.org/wiki/Standard_wire_gauge”
Here’s another reference.
“www.thethreadexchange.com/miva/merchant.mvc?Screen=CTGY&Category_Code=Hand-Sewing-Needle-Information”
