Style A Square Nibs are useful for creating block and poster, Gothic letters, ornamental borders, designs and decorations. Pen sizes decrease as numbers increase, A0 being the largest and A-6 the smallest. Pen holder sold separately. Use with Speedball No. 9451 Pen Holder, General's Cork Grip Pen Holder, Koh-I-Noor No. 130N Crow Quill Pen Holder, or Speedball Classic Pen Holders.