Model & Era: This is the classic Parker 51, produced during the height of its popularity in the mid-20th century (1900-2000 period). Nib: The primary highlight of this pen is its 14K gold nib in an Extra Fine (XF) point. This nib configuration is highly sought after for precise, detailed writing, accounting, or intricate script. The 14K gold provides a characteristically smooth and slightly springy writing experience that is superior to steel. Filling System: Based on its characteristics, this pen is likely either the early Vacumatic (vacuum-fill) or the later renowned Aerometric (squeeze-filler) system. The Aerometric system, in particular, is famous for its legendary durability and reliability, often found in fully functional condition even after decades. The exact type will be clearly visible in the photographs.