I think the button filler is perhaps the most under-rated filling system for sac pens. The mechanism is hidden under a blind cap so the pen profile remains sleek. The pressure bar collapses the entire length of the sac to get a complete fill in one go with a second press just to be sure. Thus there is no breather tube inside the sac. The pressure bar has no J bend wedged into the end of the barrel. It is simple and efficient and reliable. I think it's the best filler Parker ever made.
This pen is in excellent condition. The plastic is unmarred but for a slight darkening to the end of the grip section that is difficult to see. The aluminum button mechanism, pressure bar, cap jewel and cap clutch are clean and in perfect working order. The cap is dent free though there are a few small scuffs - see under the end of the clip. The Lucite feed is clean and as clean as new with no staining.
The nib is big and beautiful. It is not hallmarked but the 1947 Parker catalog says it is "Made of 14k gold, tipped with highest quality Osmiridium." It has a bit of bounce giving subtle character to my descenders but is otherwise firm. I've adjusted it to write a nice wet, smooth, fine line.
The cap posts easily though pen is quite long enough to use comfortably uncapped.
Length Capped - 139 mm (5.5”) Uncapped - 130 mm (5.1”) Posted - 157 mm (6.2”). Diameter Cap - 12.4 mm (0.49”) Barrel - 11.9 mm (0.47”)