These tools are an extremely good grade of carbon steel, which are also nickel plated. As far as I'm aware, all other major manufacturers don't use this quantity of carbon in their steels.
They give amazing feedback and although they have no handles, they're quite rigid, unlike SouthOrd etc so they're comortable to use. Graduated curves #3, 4 and 5 are my favo(urites.
Shame you didn't get the adjustable tension tools though...