The Simpson Strong-Bolt 2 Wedge Anchor (1/2 in. x 4-1/4 in., Type 304 Stainless Steel) is a high-performance wedge-type expansion anchor engineered for structural concrete fastening in the most demanding conditions. Built entirely from Type 304 Stainless Steel - anchor body, nut, washer, and clip - this anchor delivers long-lasting corrosion resistance across a wide variety of service environments. Its dual undercutting embossments on each clip segment enable secondary expansion should a crack form and intersect the anchor location, significantly increasing its ability to carry load if the hole expands. Code listed for both cracked and uncracked concrete and qualified for seismic design categories A through F, the Strong-Bolt 2 is an optimal choice for high-performance fastening even under seismic and high-wind conditions.

Key Features

• Code listed for cracked and uncracked concrete applications - gives engineers and contractors confidence that this anchor meets code requirements across the full range of structural concrete fastening scenarios.
• Dual undercutting embossments on each clip segment enable secondary expansion - if a crack forms and intersects the anchor location, the anchor continues to expand and carry load, providing a critical safety margin in real-world conditions.
• Qualified for static and seismic loading conditions (seismic design categories A through F) - makes this anchor suitable for projects in virtually any seismic zone, including high-wind applications where reliable load performance is essential.
• Chamfered top designed to prevent mushrooming during installation - promotes cleaner, more consistent installations and reduces the risk of damage that can compromise anchor integrity.
• Suitable for horizontal, vertical, and overhead applications - provides installation flexibility so contractors can use a single anchor type across multiple orientations on the same job site.
• Standard ANSI fractional sizes with 1/2 in. drill bit compatibility - fits standard fixtures and installs with common drill bit and tool sizes, minimizing the need for specialized equipment.
• Tested per ACI 355.2 and AC193 - independently verified performance testing means load and reliability data can be used directly in engineering calculations and code-compliant submittals.
• Full Type 304 Stainless Steel construction - resists corrosion in a wide variety of service environments, making this anchor a durable long-term solution where carbon steel alternatives would deteriorate.

Why This Product

• Built for cracked concrete where other anchors fall short - the dual undercutting clip design actively responds to crack formation by enabling secondary expansion, maintaining load capacity even as concrete conditions change around the anchor.
• Full seismic and high-wind qualification across all design categories - with code listing covering seismic design categories A through F and qualification for both static and seismic loading, this anchor is one of the most broadly approved concrete fastening solutions available for demanding structural applications.
• All-stainless construction for environments where corrosion is a concern - Type 304 Stainless Steel throughout the entire assembly means this anchor is well suited for exterior, coastal, and other corrosive service environments where long-term performance and minimal maintenance matter.
• Installs with common tools and standard drill bit sizes - compatibility with a standard 1/2 in. drill bit and 3/4 in. wrench means no special tooling is required, keeping installation straightforward and efficient for field crews.

Specifications

• Model Number: STB2-50414S4F25
• Size: 1/2 in. x 4-1/4 in.
• Drill Bit Diameter: 1/2 in.
• Thread Length: 2-9/16 in.
• Anchor Body Material: Type 304 Stainless Steel
• Nut Material: Type 304 Stainless Steel
• Washer Material: Type 304 Stainless Steel
• Clip Material: Type 304 or Type 316 Stainless Steel
• Anchor Type: Wedge-type expansion anchor
• Brand: Simpson Strong-Tie
• Packaging: Packs of 25 and Cartons of 100

Approved Applications

• Cracked concrete structural fastening applications
• Uncracked concrete structural fastening applications
• Seismic zone installations requiring code-listed anchoring solutions
• High-wind condition applications requiring reliable load performance
• Service environments where long-lasting corrosion resistance is required

Frequently Asked Questions

Is the Strong-Bolt 2 (STB2-50414S4F25) approved for use in cracked concrete?

Yes. The Strong-Bolt 2 wedge anchor is code listed for both cracked and uncracked concrete applications, making it suitable for a wide range of structural fastening scenarios.

What makes this anchor suitable for seismic and high-wind conditions?

The Strong-Bolt 2 is specifically engineered and code listed for high-performance fastening in seismic and high-wind conditions. Its dual undercutting embossments on each clip segment allow for secondary expansion if a crack forms and intersects the anchor location, significantly increasing its ability to carry load even if the hole expands.

What drill bit size is required to install the STB2-50414S4F25?

Installation of this anchor requires a 1/2-inch diameter drill bit, which matches the anchor's nominal size for a precise, reliable fit in the concrete substrate.

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

All primary components - including the anchor body, nut, and washer - are made from Type 304 Stainless Steel, and the clip is made from Type 304 or Type 316 Stainless Steel. This all-stainless construction provides long-lasting corrosion resistance, making the anchor well suited for a wide variety of service environments where standard carbon steel fasteners may be susceptible to deterioration.

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