Carriage Bolts 5/16-18 x 2-1/2 in Kit - 50 Sets Stainless Steel

In this review the Zonon carriage bolts kit is evaluated as a straightforward, no-frills fastener set for DIYers, contractors and maintenance tasks where corrosion resistance and correct sizing matter. The single biggest reason to buy is the complete package: 50 carriage bolts matched with 50 hex nuts and 50 flat washers, all in 304 stainless steel, which removes the hassle of mixing and matching parts and provides dependable corrosion resistance for indoor or outdoor projects.

Key Features

• Complete kit: The package includes 50 carriage bolts, 50 hex nuts and 50 flat washers so replacements and multiple fastenings are ready without extra purchases.
• Standard thread sizing: Threads are 5/16-18 with a 20 TPI pitch, ensuring compatibility with commonly used 5/16 in hardware and predictable fit.
• Coarse thread type: The coarse 18-8 threads provide strong bite in wood and many metal applications, improving grip and holding strength.
• Durable material: Made from 304 stainless steel for reliable corrosion resistance, making the set suitable for outdoor exposure and humid environments.
• Practical dimensions: Bolts are approximately 2-1/2 in long with an 0.71 in head diameter and 0.17 in head height, fitting a wide range of assemblies.

Who It's For

This kit is useful for homeowners, woodworkers and light contractors who need a bulk supply of matched carriage bolts, nuts and washers for decking, fencing, furniture assembly or repair jobs where a round head and square neck are desirable for a secure fit in square or drilled holes. The included hardware makes it easy to keep consistent fasteners on hand for recurring projects.

Those who should look elsewhere include users who need metric sizes, specialty coatings (such as hot-dip galvanizing) or custom-length bolts; this kit is specific to 5/16-18 coarse threads and 2-1/2 in overall length, so projects requiring other thread types or lengths will need a different product.

Pros & Cons

Pros

• Complete matched set of bolts, nuts and washers makes installations faster and reduces part mismatches.
• 304 stainless steel construction offers good corrosion resistance for outdoor and indoor use.
• Accurate 5/16-18 thread sizing and 20 TPI pitch delivers predictable fit with common 5/16 in hardware.
• Round head and square neck provide a self-locking fit in square holes for stable fastening.

Cons

• Limited to a single size and length (5/16-18 x 2-1/2 in), so buyers needing varied lengths must source additional items.
• Stainless finish may be more than needed for purely interior, hidden fastenings where a lower-cost plated fastener would suffice.

Specifications

Our Verdict

The Zonon 50-set carriage bolt kit is a solid value for people who want a matched supply of 5/16-18 x 2-1/2 in fasteners with good corrosion resistance. Its 304 stainless construction and complete complement of nuts and washers make it a practical choice for general woodworking, fencing and outdoor projects, provided the fixed size meets the job requirements.

Frequently Asked Questions

Are these bolts fully threaded?
Yes, the product description indicates full thread coverage for the carriage bolts included in the kit.

Will the square neck hold in wood?
Yes, the square neck and round head are designed to seat in square holes or bite into wood to prevent spinning during installation.

Are the nuts and washers included stainless steel?
Yes, the kit includes hex nuts and flat washers matched to the 304 stainless steel carriage bolts.