Parker 45 Fountain Pen Nib Assemblies, Feeds + Collars flat Can also be used as

Can also be used as a ballpoint

The blue device is an infrared temperature meter which is kept within reach for use to monitor the section temperature

relatively thin slots (fits Pelikan 100s and Pelikan pencils)

Idea 4 (and this is the most helpful)

Also fits the Opera and other Waterman pens the same size as the Man 100

Parker 45 Fountain Pen Nib Assemblies, Feeds + Collars flat Can also be used asNibs Assemblies are available in 14k, gold plated or steel. (Includes feed + collar). Feed only is available. All are the same. Collars only are availed with Grade Letter or unmarked. All Parker 45 collars are the same and preform the same function. The letters are irrelevant, but some people like having the letter that corresponds to their nib grade. A few unique nib feed units available