The piece described is an octagonal Montblanc Safety No. 2 with OB nib; the engraving 20B refers to the nib width OB. The fountain pen is very similarly to be classified as the documented Astoria No. 02 Octagonal Safety Filler. Cracks basically reduce the market value significantly but are emotionally hardly relevant for family heirlooms. Comparable octagonal Safetys are regularly traded on eBay and lie in market value significantly above that of a damaged Meisterstück 14, which is economically classified rather as a parts donor.