It’s literally in the paper!
"The nomenclature varies with the diameter of the fibers (and region), including ∼2 mm spaghetti (small string), ∼1.75 mm vermicellini (little worms), and ∼900 μm capellini (little hairs). The narrowest diameter mass-produced pasta is ∼800 μm capelli d’angello (angel hair), although thinner pasta lunga is produced by hand exclusively in the town of Nuoro, Sardinia: su filindeu (threads of God), which is estimated to have half the diameter of capelli d’angello and is, to the authors’ knowledge, the thinnest pasta created by hand to date "
It’s literally in the paper! "The nomenclature varies with the diameter of the fibers (and region), including ∼2 mm spaghetti (small string), ∼1.75 mm vermicellini (little worms), and ∼900 μm capellini (little hairs). The narrowest diameter mass-produced pasta is ∼800 μm capelli d’angello (angel hair), although thinner pasta lunga is produced by hand exclusively in the town of Nuoro, Sardinia: su filindeu (threads of God), which is estimated to have half the diameter of capelli d’angello and is, to the authors’ knowledge, the thinnest pasta created by hand to date "