Metallics SHC325SS5M Bolt 3-48 x 1/4 SHCS 18-8 S/S (5000 pcs)

It's a 3-48 x 1/4 inch socket head cap screw. The 3 is the machine screw diameter (#3) and 48 is threads per inch, which is the fine (UNF) thread pitch for a #3 screw. Overall length under the head is 1/4 inch, so it's a very small fastener meant for tapped holes in thin material or small-gauge enclosures and device hardware.

18-8 stainless steel, which is the 300 series austenitic grade commonly specified as Type 304 for general corrosion resistance. It's non-magnetic in the annealed condition and suited to damp interior or sheltered exterior work. For salt spray or chloride exposure, specify a 316 stainless fastener instead.

They ship 5,000 pieces per quantity. That's bulk-pack territory, so it suits a panel shop, an MRO crib, or a distributor stocking small fine-thread stainless screws rather than someone needing a handful for one repair.

Socket head cap screws (SHCS) drive with a hex key, not a screwdriver. At the #3 size you're into small hex sockets, so a precision hex key set is what's needed, and the recessed hex socket lets you reach it in a counterbored hole where a bolt head wouldn't clear.

Stainless against aluminum in a wet location is a galvanic couple and the aluminum is the part that gives up material. For indoor dry work it's a non-issue, which is where most #3 fine-thread screws land. Outdoors or in a washdown area, isolate with a nylon washer or specify a fastener closer to the base metal. Against steel there's no meaningful galvanic concern at this size.