"The Quarter Screw is capital (the quarter) fused to labor (the screwdriver) with (as always) capital at the head and labor getting the shaft. But that doesn't change the fact that it is also a tool, an object designed - explicitly - for the manipulation of Phillips-head screws." - Malcolm Gladwell
This screwdriver is a #2 Phillips-head bit (the most useful) welded to a U.S. quarter.