5/16"-18 × 4" Carriage Bolt – Grade 8, Plain Finish

Purpose‑built for long‑reach, high‑strength fastening, the 5/16"-18 × 4" Grade 8 carriage bolt is ideal for applications that demand both length and load capacity. The smooth, round head provides a clean exterior finish, while the square neck is designed to seat securely into wood or metal to prevent spinning during installation. Manufactured from heat‑treated alloy steel, this Grade 8 fastener delivers superior tensile strength for heavy‑duty and load‑bearing assemblies. The plain (uncoated) finish is well suited for controlled environments or applications where surface coatings are not required. Common uses include machinery frames, structural supports, equipment mounts, and industrial fixtures requiring extended fastening depth and dependable strength.