3/8 x 4-1/2 Lag Screw Kit (50 Pack) - Hot Dip Galvanized

In this review of the 3/8 x 4-1/2 Lag Screw Kit the bottom line is straightforward: it is a practical, industrial-style fastener kit for outdoor and structural projects that need corrosion resistance and consistent hardware in bulk. The kit includes 50 Grade 307A lag screws and 50 USS flat washers, and the single biggest reason to buy is the hot-dip galvanized finish, which provides superior rust protection for use with ACQ treated lumber and other outdoor builds. For DIYers or contractors needing a simple, reliable kit, this review finds the set delivers predictable performance at a reasonable price.

Key Features

• Kit contents: Includes 50 lag screws and 50 USS flat washers so you have matched hardware for multiple fastenings without hunting for washers separately.
• Corrosion resistance: The hot-dip galvanized finish offers strong protection against rust, making these screws suited to outdoor and pressure-treated lumber use.
• Industrial grade: Manufactured to meet ASTM A307 and ASME B18.2.1 standards, the fasteners are intended for commercial and heavy-duty residential applications.
• Dimensions you can rely on: At 3/8 in diameter with a 4-1/2 in length and a 9/16 in head width the screws are sized for deep embedment in wood framing and structural connections.
• Installation guidance: The maker recommends a pilot hole, which helps prevent splitting and makes driving the 4-1/2 in lags easier with hand or impact tools.

Who It's For

This kit is aimed at carpenters, deck builders, and homeowners working on outdoor projects where corrosion resistance matters, such as decks, pergolas, posts, and other wood-to-wood structural connections. The quantity and matched washers make it convenient for medium-size jobs or for stocking a job truck.

Those who need specialty coatings, stainless steel fasteners, or metric sizes should look elsewhere, and if ultimate tensile strength is the sole priority without concern for coating, a hardened structural bolt or a different grade may be preferable.

Pros & Cons

Pros

• Hot-dip galvanized coating provides durable rust resistance for outdoor use with ACQ treated lumber.
• Includes 50 USS flat washers, saving time and ensuring the load is distributed correctly under the head.
• Meets recognized standards like ASTM A307 and ASME B18.2.1, which supports consistent manufacturing quality.
• Bulk pack of 50 screws is good value for multiple fastenings or job site convenience.

Cons

• Some customers report mixed hold capacity and occasional breakage under extreme load, so these are best used where specified application limits are observed.
• Pilot hole is recommended, so installation takes a bit more prep than driving smaller or self-drilling fasteners.

Specifications

Diameter	3/8 in
Length	4-1/2 in
Head width	9/16 in
Kit quantity	50 screws + 50 washers (100 pcs total)
Washer size	3/8 USS flat washer, 1 in OD
Coating	Hot-dip galvanized
Standards	Meets ASTM A307, ASME B18.2.1, ASME B18.21.1, ASTM F2329

Our Verdict

Overall, this 3/8 x 4-1/2 lag screw kit is a sensible, value-oriented choice for outdoor timber work when corrosion resistance and matched hardware count. It is best for general deck and structural carpentry where hot-dip galvanizing and compliance with common fastener standards matter; those needing higher tensile strength or specialty materials should evaluate alternate grades. For most users tackling outdoor wood projects, this kit offers reliable protection and convenience for the price.

Frequently Asked Questions

Are these suitable for ACQ treated lumber?
Yes, the hot-dip galvanized finish is specified as suitable for use with ACQ treated lumber.

Do I need a pilot hole?
Yes, a pilot hole is recommended to reduce splitting and to make driving the 4-1/2 in lag screws easier.

What does the kit include?
The kit contains 50 Grade 307A hex lag screws and 50 USS flat washers for a total of 100 pieces.