Size: Length - 5 1/8 inches.
I see very few Parker 51 ballpoints, and this is the first one with the Custom cap that I have been able to offer for sale. It is in excellent condition with no real damage at all, just a few very fine and wispy scratches to the body of the cap are the only damage I can see on this pen. It is a U.S. made pen, in the Midnight Blue colour that was not manufactured in the UK. It is not an early example, having the barrel threads in the same lucite as the barrel is made from. I would say early to mid-1960s. It is fitted with a modern Parker ballpoint refill in black that is working perfectly. You can get a huge range of different refill types to fit it including gel, rollerball, fine liner, etc.
I have fully serviced this pen. It works very well.