Its the one and only Parker 51, titan of the vintage pens. Certainly the best-selling vintage luxury pen of all time, this is the 1950s version with an aerometric squeeze-bar filler. Black with a gold-filled cap, it is a go-to crowd pleaser. The cap has a couple little dings and scratches from use. The hood and barrel of the pen likewise show wear from use. Nevertheless, the original "pliglass" ink sac still works great. You'll write a smooth medium line with its 14k gold nib. The blue diamond on the pocket clip indicates this might be an earlier cap or an older replacement clip for the pen. The barrel part of the pen was made a few years after the clip/cap. 13.8cm capped.