IMSCREWS 5/16"-18 x 3" Heavy-Duty 304 Stainless Steel Carriage Bolts (20 PCS)

Substantial Strength for 4x4 Posts and Timber Construction
The IMSCREWS 5/16" x 3" carriage bolt is engineered for structural projects requiring significant shear resistance and a professional, tamper-resistant finish. With a robust 5/16-inch diameter and a precise 3-inch length, these bolts are the ideal choice for securing deck railings to 4x4 posts or connecting dual-layered 2x4 lumber (actual 3" thickness). The full thread design ensures maximum versatility, providing a snug and permanent connection across various material combinations. Built for durability, they offer the stability required for outdoor structures, pergolas, and heavy-duty timber framing.

High Durability and Safety-Focused Design
Forged from premium 18-8 (304) stainless steel, these fasteners are highly resistant to rust and corrosion in coastal or humid environments. The smooth round head offers a clean, low-profile appearance that reduces snagging hazards, making them a safe choice for children's playground equipment, residential benches, and exposed deck stairs. The integrated square neck prevents the bolt from spinning during installation, allowing for easy, one-sided fastening with a single wrench from the nut side.

Specifications:
- Thread Size: 5/16"-18 Coarse (UNC); Length: 3" (Measured from Under Head)
- Material: 304 (18-8) Stainless Steel; Full Thread

Pro-Tips:
1. Use a 5/16" drill bit to ensure a snug, structural fit for the square neck.
2. Pair with stainless steel flat washers and hex nuts on the nut side to distribute structural load and protect wood fibers.

Key Features

• Industrial 3 Penetration: Expertly designed for through-bolting thick timbers, such as joining two 2x4s (3 total) or securing heavy-duty brackets to structural 4x4 posts.
• Reinforced 5/16 Strength: The 5/16 shank offers a significant boost in load-bearing and shear resistance over standard 1/4 bolts, ensuring safety in structural applications.
• Marine-Grade 304 Stainless: Forged from 18-8 (304) stainless steel, providing superior rust protection in coastal environments, humid gardens, and with treated lumber.
• Tamper-Resistant Safety Head: The smooth round head offers a clean finish without sharp edges¡ªideal for public benches, playgrounds, and child-safe backyard structures.
• Self-Locking Square Neck: The precision square shoulder bites firmly into wood fibers, locking the bolt so you can easily tighten the nut with one wrench from the opposite side.

Specifications

• ASIN: B0F2F8G9Q9
• Internal SKU: IMS0809
• Size: 5/16"-18 x 3"
• Material: Stainless Steel
• Finish: Stainless Steel
• Head Style: Round
• Package Quantity: 20