On the Pelikan 100 and 100N a cork piston seals the ink reservoir. The cork dries out over the decades, so that almost every unrestored example needs an overhaul before use; an old pen that still draws cleanly when you buy it is the exception. Once the seal has been renewed and the pen thoroughly cleaned, these fillers are fully serviceable again.
The version determines the price. Green marbled pieces are the standard variant and the most commonly found; all-black bodies as well as early models without a cap band are considered markedly rarer and are dear accordingly: in 2007 neither a black 100 nor a black 100N was to be had for 100 euros, while green examples turned up regularly at flea markets. According to collectors, the nib widths of that period were designated EEF, EF and F among others, and KEF and KF for ball grinds.