About:
This is a first generation Parker 51 aerometric filler (1948-1950).  Identified by the gold filled clip on a Lustraloy cap, an option discontinued by parker in 1950.  This particular pen has a name and 1949 date scratched on the filler unit (see photo), which simply reiterates what the pen's characteristics are telling use.  
 
Condition:
The pen is in overall very good condition with a nice dark, rich forest green coloring, there are no cracks or personalization (name and date scratched on filler unit). The pen's cap and barrel have some light surface scratches. The GF clip is firm and in nice condition, the cap jewel is also firm and in good condition, all as shown in the photos. The pen has been flushed, the nib unit ultrasonically cleaned and it has been ink tested.  The pen fills nicely and writes well.