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The HILLMAN FASTENERS 240183 is a 3/8-16 x 4-1/2 inch steel carriage bolt sold in a 50-pack. It features a round dome head and a square neck that bites into wood or soft material to prevent rotation during installation. The coarse thread pattern provides strong holding power in wood-to-wood and wood-to-metal connections. This bolt is a standard choice for structural fastening tasks in residential construction, decking, framing, and general fabrication. Carpenters, general contractors, and maintenance technicians typically keep these on hand for high-volume fastening applications where consistent clamping force is required.
This carriage bolt is suited for through-bolt applications in wood framing, deck ledger connections, post-and-beam assemblies, and similar structural joints. The coarse 3/8-16 thread mates with standard hex nuts and washers. The 50-pack quantity makes it practical for job-site use where multiple fasteners of the same size are needed in a single session.
Designed as a standard 3/8-16 coarse-thread carriage bolt compatible with matching hex nuts, coupling nuts, and flat washers following ASME B18.5 dimensional standards for round-head square-neck bolts.
Carriage bolts are installed by driving the bolt through a pre-drilled hole sized to the shank diameter, then seating the square neck flush by tapping the head with a hammer. A flat washer and hex nut are threaded onto the exposed end and tightened with a wrench — no wrench is needed on the head side once the neck is seated. Follow applicable building code requirements, including IRC or IBC provisions, when using carriage bolts in load-bearing or ledger connections. Do not overtighten in soft wood species, as the square neck can pull through the substrate.
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