Allen, 18-8, 16, 1-3/4"

US Fasteners, Allen, 18-8, 16, 1-3/4"
Socket screws Screws with an Allen wrench drive.	Set screws Screws with no head and machine threads for use in a tapped hole.
Sex bolts & Mating screws Sex bolts resemble machine screws, but with internal threads, and can be used with either specialized mating screws or standard machine screws. Also known as barrel nuts and Chicago bolts.