Name this bolt, please.

[John Delacour]

At 18:22 -0700 21/3/08, Jason Kanter wrote:

>It's emphatically NOT a thumb screw -- it's a "quarterturn screw". 
>Thumb screws have a cylindrical, knurled head.

I'll go for thumb screw -- it has far longer currency and is defined 
in Webster's Dictionary as "a screw whose head is flattened at the 
side or knurled so that the screw may be turned by the thumb and 
forefinger".

Thank you, everybody, for the naming.

JD