We just released two new fountain pens - the Crowquill Fountain Pen and the Hawkquill Fountain Pen. The hawkquill nib is slightly larger than the crowquill so it requires a larger feed. Other than that, the two pens are identical. When you want to replace the nib, slide off the old nib and press on the new nib. You can adjust the position of the nib to increase or decrease the flow of ink.