More to the point is that the dark bottom cheesehead Torx screws have a metal thread to mate with holes in the metal chassis, and the top 'silver' cheesehead screws have a coarse thread to mate with the corresponding holes in the bezel without ripping the thread out of the ABS plastic when they are overtightened. And to restate the already well-known, all of the screws have recesses in their heads to mate with a Torx-15 driver (splined cylindrical tip) that has at least an 8-in shaft. The driver doesn't need to have a central (axial) hole in the tip because the screws that Apple used are not security screws (Resistorx or Pin-Torx).

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