#4, Slotted flat head

US Fasteners

Slotted flat head

Wood screws

Screws with a smooth shank and tapered point for use in wood.
Slotted flat head

Sheet metal screws

Screws with large threads for use in sheet metal sometimes also used in plastic, fiberglass, or wood.
Slotted flat head

Machine screws

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