5/16" x 4-1/2", US, Zinc plated steel

Bolts with hexagonal heads and machine threads for use with a nut or in a tapped hole. Also known as hex cap screws or machine bolts.

Screws with machine threads for use with a nut or in a tapped hole.

Bolts with no drive and machine threads for use with a nut.

Large wood screws technically called lag screws.

Bolts or screws with a circular ring on the head.