The Osprey nib protector is designed to protect your nib and user during handling.

Spare replacement plastic guard covers are now available to fit your own dip nibs or nib units in 2 sizes: 

1) Regular is 25mm/1 inch in length, and has an inner diameter of 9mm/ 0.35 in. Recommended for protecting nib sizes 6 and lower such as #5.5, regular size 6

2) The large is about 37mm/ 1.45inches in length with an inner diameter (ID) that is slightly larger at 12.7mm/0.50". These are recommended for size 6 and above such as #6 Flex nibs, Size 8 , etc. The large protector not only covers the nib unit but also extends slightly onto the section that seats the nib unit.