Steel Black Oxide & Oil Carriage Bolts 3/8-16 x 4 are built for dependable, wood-to-wood and machinery assemblies. Crafted from durable steel, these carriage bolts feature a black oxide finish with an oil coating that helps resist wear and provides a handsome, low-profile appearance.

Key specifications

• Diameter: 3/8 in
• Thread: 3/8-16 UNC
• Length: 4 in
• Finish: Black oxide with oil coating
• Head style: Carriage bolts with a square under the head to prevent turning
• Material: Steel

Why choose these carriage bolts?

Carriage bolts are a classic choice for woodworking and furniture projects due to their clean, rounded heads that sit flush in countersunk surfaces and their square neck underneath to resist turning when tightened. The 3/8-16 size is a versatile fit for many standard fastener applications, and the 4-inch length offers strong engagement in thicker materials.

Applications

Ideal for decking, wooden structures, furniture assembly, gate hardware, and other projects where a secure, aesthetically discreet bolt is desired. The steel core provides strength, while the black oxide and oil finish adds a stealthy look and smoother installation.