A barrel nut (or dowel nut) is a cylindrical fastener with internal threads at one or both ends, used to connect two threaded rods, screws, or pipes. Its length is generally greater than its diameter, and the exterior can be smooth or feature a hexagonal drive. Common types include: double‑ended internal thread (for rod extension), single‑ended internal thread (mating with a bolt into a blind hole), and through‑hole plain bore (used with a wood screw for timber connections). They offer concealed installation, clean appearance, and strong joint strength. Typical applications include wooden furniture, display racks, scaffolding pipe connections, and sports equipment.
Customizable options:

Materials: Carbon steel (C1008/C1045), alloy steel (SCM435/40Cr), stainless steel (SS304/SS316), brass, aluminum, nylon, zinc alloy (die‑cast), etc.

Surface finishes: Electroplated zinc (blue/white, yellow, black), nickel plating, chrome plating, black oxide, phosphating, hot‑dip galvanizing, Dacromet, painting, etc.

External features: Smooth cylinder, external hexagon, straight/Phillips/Torx® drive slot, anti‑rotation knurling, flange, cross hole (for cotter pin)

Other variables: Thread size (M2–M12), overall length (10mm–50mm), outer diameter, internal thread depth and location, through‑hole diameter can be manufactured to customer drawings.
Widely used in furniture connections (e.g., table/chair leg cross braces), scaffold tie rods, flagpole bases, display shelving, fitness equipment, and door/window handles.