Fisher Space Pen's Cap-O-Matic pen has the pressurised ink you know from their Bullet Pens. It enables writing upside down, in every angle, underwater, on top of grease and in extreme temperatures.

The M4 Cap-O-Matic Space Pen has been available for many years in a variety of different colours & finishes, but now for the first time, it's available in raw brass.

This pen has a PR4 pressurised black medium ink cartridge.