The Simpson Strong-Bolt 2 1/2 in. x 4-3/4 in. Wedge Anchor in Type 304 Stainless Steel is a wedge-type expansion anchor engineered for high-performance concrete fastening in the most demanding structural, seismic, and high-wind applications. Dual undercutting embossments on each clip segment enable secondary expansion should a crack form and intersect the anchor location, significantly increasing the anchor's ability to carry load if the hole expands. Combined with Type 304 Stainless Steel construction, this concrete anchor delivers long-lasting corrosion resistance across a wide variety of service environments - making it a trusted choice for contractors and engineers who need reliable holding power in both cracked and uncracked concrete.

Key Features

• Code listed for cracked and uncracked concrete applications - gives installers the flexibility to use a single anchor solution across a broad range of structural conditions without compromising compliance.
• Qualified for static and seismic loading conditions (seismic design categories A through F) - ensures the anchor meets the requirements for high-risk seismic zones and high-wind environments, reducing specification risk on critical projects.
• Dual undercutting embossments on each clip segment enable secondary expansion - if a crack intersects the anchor location and the hole expands, the anchor continues to carry load rather than losing holding strength.
• Chamfered top designed to prevent mushrooming during installation - protects the anchor threads during driving, resulting in a cleaner, faster installation with fewer damaged fasteners.
• Suitable for horizontal, vertical, and overhead applications - provides installation versatility across orientations, reducing the need to stock multiple anchor types for different jobsite conditions.
• Standard ANSI fractional sizing (1/2 in. diameter) - fits standard fixtures and installs with common 1/2 in. drill bits and a 3/4 in. wrench, so no specialized tooling is required.
• Tested per ACI355.2 and AC193 - independent third-party testing gives engineers and inspectors confidence that load values are backed by recognized industry standards.
• Made from Type 304 Stainless Steel - provides long-lasting corrosion resistance for service environments where carbon steel anchors would degrade, reducing maintenance and replacement costs over time.

Why This Product

• Built for the most demanding concrete fastening conditions - the Strong-Bolt 2's secondary expansion capability and qualification through seismic design categories A through F make it one of the few wedge anchors specifically engineered to maintain load capacity even when concrete cracks around the installed anchor.
• Stainless steel construction where it matters most - Type 304 Stainless Steel construction provides long-lasting corrosion resistance for installations in wet, coastal, or chemically aggressive environments where a standard zinc-plated anchor would deteriorate prematurely.
• Designed to install fast with no special tools - the chamfered top, standard ANSI fractional sizing, and compatibility with a common 1/2 in. drill bit and 3/4 in. wrench mean crews can work efficiently without sourcing specialty equipment or drill bits.
• Broad code compliance reduces project risk - with testing per ACI355.2 and AC193 and code listing for both cracked and uncracked concrete, this expansion anchor simplifies specification approval and inspection sign-off on commercial, industrial, and institutional projects.

Specifications

• Model Number: STB2-50434S4F25
• Coating/Material: Type 304 Stainless Steel
• Size: 1/2 in. x 4-3/4 in.
• Drill Bit Diameter: 1/2 in.
• Thread Length: 3-1/16 in.
• Component Material - Anchor Body: Type 304 Stainless Steel
• Component Material - Nut: Type 304 Stainless Steel
• Component Material - Washer: Type 304 Stainless Steel
• Component Material - Clip: Type 304 or Type 316 Stainless Steel
• Packaging: Packs of 25 and Cartons of 100

Approved Applications

• Cracked concrete installations
• Uncracked concrete installations
• Seismic condition applications
• High-wind condition applications
• Service environments requiring long-lasting corrosion resistance

Frequently Asked Questions

Is the Strong-Bolt 2 STB2-50434S4F25 suitable for use in cracked concrete?

Yes. This anchor is code listed for both cracked and uncracked concrete applications, making it a versatile choice for a wide range of structural installations.

What makes the Strong-Bolt 2 perform well in seismic and high-wind conditions?

The Strong-Bolt 2 features dual undercutting embossments on each clip segment that enable secondary expansion should a crack form and intersect the anchor location. This feature significantly increases the anchor's ability to carry load if the hole expands, making it especially reliable under seismic and high-wind conditions.

What drill bit diameter is required to install this anchor?

Installation requires a 1/2" diameter drill bit, which matches the anchor's 1/2" diameter for a proper fit in concrete.

Why is stainless steel used for all components of this anchor?

All primary components - including the anchor body, nut, and washer - are manufactured from Type 304 Stainless Steel, and the clip from Type 304 or Type 316 Stainless Steel, to provide long-lasting corrosion resistance across a wide variety of service environments where standard carbon steel anchors may be prone to deterioration.

Note: Product dimensions and/or thread length may differ from picture. Please see the item description above for specifications.