Prime‑Line carriage bolts provide strong, dependable fastening for wood‑to‑wood or wood‑to‑metal applications commonly found in home improvement and repair projects. Featuring a smooth, rounded head with a square neck, these bolts are designed to prevent turning during installation and deliver a clean, finished appearance on visible surfaces. Ideal for use in outdoor furniture, decks, fencing, gates, signage, and structural assemblies, Prime‑Line carriage bolts are intended for use with same‑size matching nuts and washers to ensure proper fit, improved load distribution, and a secure long‑lasting hold. Manufactured from quality materials for durability and corrosion resistance, they install easily with standard tools and perform reliably in both indoor and outdoor environments. Trusted by DIY homeowners and professionals across the U.S., Prime‑Line carriage bolts make it easy to complete projects with strength, stability, and a professional finish. Size: 5/16 inch-18 X 1 inch Features a smooth rounded head as opposed to a standard hex head Square shoulder allows for nut to be tightened or loosened Often used in cases where a protruding bolt head could cause injury Nuts and washers not included, ensure washers and nuts are same diameter UPC 049793133816 ASIN B074ZXQTF4 Brand PRIME-LINE Color Zinc Model 9062830 Set Name Prime-Line Zinc Plated Carriage Bolt Set (5/16 in. -18, Grade A, 50 Pack) Head Type Domed Size Name 5/16 in. -18 Metal Type Zinc,Steel Unit Count 1 Count Item Weight 1.4 pounds Part Number 9062830 Thread Size 5/16 -18 Thread Type Unc Drive System Square Finish Types Zinc Plated Grade Rating Grade A Manufacturer Prime-Line Thread Class Others Thread Style Right Hand Fastener Size 5/16 Fastener Type Carriage Bolt Item Diameter 0.31 inches Item Hardness Grade A Material Type Alloy Steel Item Type Name Carriage Bolt, 5/16 in-18 X 1 in, Zinc Plated Steel, Pack of 50 Exterior Finish Zinc Item Dimensions 1 x 4 x 2 inches Number Of Items 50 Thread Coverage Partially Threaded Number of Pieces 50 Outside Diameter 0.31 inches Screw Head Style Domed Screw Point Style Square Point Manufacturer Grade Grade A Included Components Carriage Bolt Compatible Groove Diameter 0.33 inches Global Trade Identification Number 00049793133816