Good night dear forum users. During a unboxing video of Surface Pro 3, I realized that the pen requires a small internal battery that goes just inside the box. I wonder then what should be the difference between SP2 and SP3 pens. Is there any significant improvement in the new version? If yes, is there any pen sold separately which could provide better results as in SP3? Ps: this is the video [video=youtube;uXU63V1O2eE]https://www.youtube.com/watch?v=uXU63V1O2eE[/video] Thank you!