Osprey Pens introduces Bock compatible special grind nibs: Broad-Stub (B S) and Double Broad Stub (BB S)

Stub: A Stub nib tipping material is ground flat on the end. This type of a nib produces a narrow line on the cross stroke, broad on the down stroke. It mimics calligraphy (without doing anything different!) unlike flex nibs, which require pressure to change the line width. A stub nib is (usually) a broad nib that has a flat end but smoothly rounded corners. 

These Nib Unit works with pre-filled ink cartridges or with bottled ink using a  generic international converter

These units will not fit your regular Scholar or Milano fountain pens, as they are made specifically to match a Bock housing thread pattern.