The Sidewinder S G2 is the first version of front attachment on the TC52 Phone Holster and the reason for the name S G2 is that it holds and locks in 1x Sharpie Fine Point and 1x Pilot G-2 05 Pen. Other pens and markers may fit but won't lock in as well as those two.
Next to the screw holes you can attach pocket knives, multitools or other small pieces with a clothing hook.
The Sidewinder comes with 2x screws, 2x rubber gaskets and 2x posts