Uschi Van Der Rosten products. I cain't recommend doing business with them.

[Rhino]

I got a spool of this.

INFIR1101B Infini Model Black Lycra Ship Rigging - Medium 110 Denier (0.121mm x 145 feet)

spruebrothers.com

And Berkshire Junction EZ Line.

EZ Line - Berkshire Junction

But you're right, these folks are sourcing this somewhere. where?

Yay Bob!!
Sprue brothers is out of stock, but eBay had the Infini Model 0104B 40 denier 145 foot roll from a shop in Houston, TX.
I ordered one to evaluate this product. I still have a 1/48 Curtiss RC3-2 to rig.

 

[Rhino]

40 Denier scales out to .0027 mm. Bob has the exactly right diameter at 110 Denier or .0132 mm or .0005 inches. This Lycra material is flexible and stretchy. Perfect! I can see why MiG Ammo would market 5-foot lentghs. Whoe needs 145 feet for any one project, but you pay as much for 5 feet as you do for 145 feet. Not lots of really sharp Policework left to do on this one.

In other words, IB meine Unterkleidung, Herr Glass.

Orders can be made from Infini Model in South Korea, but I went back to eBay, paid $2.00 more a roll and reasonable USPS Shipping from Katy, Texas. Mystery solved.