Metallics JBLS14SS50 Bolts 5/16 x 3 Hx Lag Blt SS (Jar 50)

Not on its own. A lag bolt is a wood fastener. To put one into concrete or block you need a lead or plastic lag shield set in a drilled hole, and the shield has to be sized for a 5/16 inch lag. Driving it straight into masonry will not hold. For steel framing, use a machine bolt or self-drilling screw instead.

Stainless steel is the reason to pick these. The 5/16 x 3 lag bolt is stainless rather than plain or zinc-plated steel, so it holds up in wet exterior work, coastal air, and damp mechanical or utility spaces where a plated fastener would rust and stain the surface it's driven into.

They're the fastener for anchoring into wood framing: mounting strut and channel to joists, hanging panels and enclosures on plywood backboards, securing transformer and disconnect brackets, and fastening exterior light or sign standoffs. Metallics catalogs this one with its electrical supply line, and the 3 inch length gives enough thread into a stud or blocking to carry a real load.

No nut. A lag bolt cuts its own thread in wood, so you drill a pilot hole and drive the hex head with a wrench or socket. For a 5/16 inch lag you'll want a 1/2 inch socket on most hex heads, and a washer under the head if you're clamping through a bracket or a soft material. These ship as bolts only, 50 per jar, with no nuts or washers included.

For dry interior framing, a zinc-plated or hot-dip galvanized lag of the same 5/16 x 3 size does the job and is the usual choice. Go stainless, as this one is, when the fastener sees weather, moisture, washdown, or pressure-treated lumber, or when you're bolting to stainless or aluminum and want to avoid a dissimilar-metal problem.