SH4688  Sheaffer Nib for 1950s-60s Cartridge Filler fountain pen style nib unit with original inspection tag marked “Max Open Back”.  This would have been what was referred to as a “Perfect Sample”  Medium round point.   (1 avail) 

Durex No.4 Fine Nib - fits Esterbrook Renew Points.

Esterbrook Renew Point #9556 Firm Fine Writing. Master Durachrome. Esterbrook 9000 series of nibs are all tipped with an iridium ball at the point.

Esterbrook Renew Point #2668 Firm Medium General Writing. Solid Durachrome. Esterbrook's 2000 series nibs are "rolled" or "folded" at the tip to form the writing point.

Esterbrook Renew Point #2550 Firm Extra Fine Posting. Solid Durachrome. Esterbrook's 2000 series nibs are "rolled" or "folded" at the tip to form the writing point.