The retractable Stylus is only available on a 58mm knife called the Stylus. It has a nearly identical design to the retractable pen found on a number of 58mm knives such as the Signature and Manager II. The Stylus has the same metal shaft as the pen, but the ball point tip is replaced with a smooth plastic tip making it suitable for writing on touch screen surfaces.
The Stylus is replaceable like the pen, and it is possible to replace the retractable 58mm Pen in any model with a stylus.