From the manufacturer:
Utilizing the same historically proven processes specifically catered to each individual nib’s design, Speedball takes painstaking measures to ensure that each of our nibs meets even the most discerning standards. In addition to the highly-trained team that is responsible for making your Speedball nib, we have a dedicated member of our Speedball family that hand-inspects all nibs, one by one, that passes through production. That way, our valued artists never have to worry about their writing experience ahead when using a trusted Speedball nib. Offered in a range of widths and varying degrees of stiffness in order to provide artists the maximum amount of control, Speedball’s Pointed and Crowquill Pen Nibs are made from the finest steel and hand-crafted in the USA.
99 Nib: This extremely flexible nib features an extra fine point and is capable of producing thick swells with minimal pressure. Perfect for artists with a light touch working on smooth papers.
101 Nib: Perfect for use to create Copperplate or Spencerian scripts, the #101 is durable and steady. Ideal for expert and student scribes alike, the #101 is great for larger scale lettering projects.
102 Nib: The #102 is super fine and flexible.
108 Nib: The #108 is best for use for cross-hatching, flourishing and lithography.