Yeah, I get that, but the security torx with the pin in the middle seems a bit of overkill for slapping together a bathroom. It's not like that pin is needed to guide a bit into the slot (is it?) and it seems the hollowing would lessen the lifespan of a bit used in a power tool.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"