1/4", External hex

US Fasteners

Hex head

Sheet metal screws

Screws with large threads for use in sheet metal sometimes also used in plastic, fiberglass, or wood.
Hex bolt

Hex bolts

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.
Flange bolts

Flange bolts

Flange bolts have a flange on the bottom of the head that distributes the load like a washer.
Machine screws hex washer head

Machine screws

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

Lag bolts

Large wood screws technically called lag screws.
Roofing screws

Roofing screws

Screws designed to be used in metal roofing applications and are available in a variety of colors.
Anchors

Anchoring products

Fasteners for anchoring in stone, concrete, brick, and drywall, etc.