Socket screws have an allen wrench drive.

Socket flat head, 8, 6-1/2"

Socket flat head screw

Socket flat head

Flat heads are countersunk (cone shaped under the head) with a flat top. Allen (hex socket) drive is a six-sided recess for use with an Allen wrench (hex key).

See also

Socket product

Metric socket screws

Screws with an Allen wrench drive.

Set screw

Set screws

Screws with no head and machine threads for use in a tapped hole.

Shoulder bolt

Shoulder bolts

Screws with an unthreaded shoulder that is larger in diameter than the threads. Also known as stripper bolts.