That is called a "clutch head screw" and it takes a specially-designed driver. Those things were one of the first attempts at automated, or at least speeded-up production lines, as they could be stuck onto a magnetic-tip driver, and they wouldn't fall off as easily as a slotted-head screw, or a Phillips screw. Snap-on and a few other tool manufacturers still sell those drivers, in 3 or 4 different sizes.
Jerry

Last edited by Hotrod Lincoln; 01/09/2010 1:57 AM.
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