3/8 in x 3 in Carriage Bolt Kit (25 Pack) - Ceramic Black Rust

Our review of this 3/8 in x 3 in carriage bolt kit finds it best suited to homeowners and contractors who need a durable, visually discreet fastener for outdoor timber projects. The biggest reason to buy is the five-layer ceramic black ruspert coating that promises improved rust resistance compared to plain galvanized fasteners, giving a semi-flush, finished look for decks, pergolas, and pavilion work. The kit format with washers and nuts makes it convenient for multi-point jobs, and the Grade 307A bolt strength paired with grade 2 nuts covers most common structural fastening needs.

Key Features

• Complete kit: Includes 25 carriage bolts, 25 USS thick washers, and 25 hex nuts so a single purchase covers entire small projects without searching for matching hardware.
• Protected finish: Five-layer ceramic black ruspert coating offers greater rust resistance than standard galvanized finishes and keeps exposed fasteners looking uniform outdoors.
• Semi-flush head: The carriage bolt flat head yields a semi-flush appearance, which is ideal for visible timber connections on decks, gazebos, and pergolas.
• Clear sizing: 3/8 in diameter and 3 in length with a 0.813 in head diameter make it straightforward to plan drill sizes and embedment for structural joints.
• Simple installation: Nut wrench size 9/16 in and 1 in washer outside diameter means common tools fit and distribute load effectively on wood members.

Who It's For

This kit is for DIYers, deck builders, pergola makers, and small contractors who want a coordinated set of carriage bolts with matching washers and nuts in a black finish. It suits projects where appearance matters and a semi-flush carriage head is preferred over exposed hex heads.

Those building extremely heavy structural connections that require higher grade hardware or who need stainless corrosion resistance for marine environments should look elsewhere; the Grade 307A bolt with grade 2 nuts and a ruspert coating is durable for most outdoor woodwork but is not a stainless alloy for saltwater conditions.

Pros & Cons

Pros

• Well matched kit reduces time spent sourcing compatible washers and nuts for each bolt.
• Ceramic black ruspert coating provides noticeably better rust resistance than plain galvanized fasteners in typical outdoor settings.
• Semi-flush carriage head delivers a clean, finished look on visible timber surfaces.

Cons

• Some customers reported mixed long-term rust resistance in very exposed conditions, so performance may vary by environment.
• Grade 2 hex nuts are adequate for many jobs but not intended for the highest strength structural applications.

Specifications

Diameter	3/8 in
Length	3 in
Head diameter	0.813 in
Nut wrench size	9/16 in
Washer outside diameter	1 in
Kit contents	25 bolts, 25 USS thick washers, 25 hex nuts
Coating and grade	5-layer ceramic black ruspert coating; Grade 307A bolts, grade 2 nuts

Our Verdict

The 3/8 in x 3 in carriage bolt kit is a practical, good-value choice for outdoor wood projects where appearance and improved rust resistance matter. The matched washers and nuts and the semi-flush head make installation tidy and efficient, while the ceramic ruspert coating gives better corrosion protection than standard galvanized options for most residential and light commercial uses.

Frequently Asked Questions

Are these bolts suitable for deck framing?
Yes, they are suitable for typical deck connections and visible deck trim where a semi-flush finish is desired, though very heavy structural framing may require higher grade fasteners.

How much corrosion protection does the coating provide?
The five-layer ceramic ruspert coating offers approximately twice the rust resistance of basic galvanized finishes in common outdoor conditions, but performance varies with exposure.

Do washers and nuts match the bolts?
Yes, the kit includes 25 USS thick washers and 25 hex nuts sized to fit the 3/8 in bolts for a complete matched set.