[6] Based on technology developed by N-trig[7] (a separate company at the time, though subsequently acquired by Microsoft),[8] the Surface Pro 3 version lacks the eraser tip present in the previous generation; erasing is done by drawing over the ink strokes while holding down one of two physical buttons on the side, above the button used for right-clicking.

[9] A third button, located at the back of the pen, sends a Bluetooth signal to a paired Surface PC which instantly opens OneNote, even when the device is locked (although advanced editing functions are disabled in this case).

Unlike the previous pen, this version can be stowed away by sliding it into a self-adhesive felt loop which can be attached to the Surface Type Cover (optional extra).

[13] The default options are: single-click opens OneNote, double-click takes a screenshot, press-and-hold launches Cortana.

They integrate with the built-in Whiteboard app and, unlike the Surface Pen, can both be used for simultaneously inking by multiple users.

It has 21 milliseconds of latency, making it "the fastest digital pen on the planet” at the time of release, according to Microsoft.

The Slim Pen is powered by a non-removable internal rechargeable battery which is charged wirelessly by resting it in the cradle of a supported cover or an optional charger.