Two small nits about second part of this passage: electrovibration — the rapid attraction and repulsion of the skin to an insulated ground plane (such as

Two small nits about second part of this passage: electrovibration — the rapid attraction and repulsion of the skin to an insulated ground plane (such as brushed aluminum) - Metal in unibody MBPs is sandblasted [1] rather than brushed [2] to give it its texture; - Neither sandblasting nor brushing aluminum gives it thick enough oxide layer (Al2O3), and it is that layer that makes actual insulation. Instead this layer is formed by the way of anodizing [3], complementary and separate process. [1] https://en.wikipedia.org/wiki/Abrasive_blasting https://en.wikipedia.org/wiki/Abrasive_blasting [2] https://en.wikipedia.org/wiki/Brushed_metal https://en.wikipedia.org/wiki/Brushed_metal [3] https://en.wikipedia.org/wiki/Anodizing https://en.wikipedia.org/wiki/Anodizing