1/4-20 x 4 in. Round Head Combo Machine Screws – Steel Zinc – 100qty
https://nsiindustries.com/product/1-4-20-x-4-in-round-head-combo-machine-screws-steel-zinc-100qty/
These screws have finer threads than typical screws, requiring a pre-drilled hole and are perfect for joining metal parts in machinery and construction. With a combo drive, these fasteners can be used with slotted and Phillips screwdrivers and drill bits.