S-92949A845 1/4"-28 x 1 3/8" ASME B18.3, ASTM F879 Stainless Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance thanks to 18-8 Stainless Steel construction and passivated finish, ensuring long-term reliability in harsh environments.
• Exceptional thread precision with Class 3A UNF fine threads for secure, vibration-resistant fastening and reduced risk of cross-threading.
• High mechanical strength offering 70,000 psi tensile strength and Rockwell B55 hardness for demanding load-bearing applications.
• Efficient installation and removal with a 5/32" hex drive, providing positive torque transfer and reducing tool slippage.
• Optimized head design featuring a rounded button profile that minimizes protrusion and improves aesthetic integration.
• Full threading along the 1-3/8" length ensures maximum grip and uniform stress distribution in assembled components.
• Compliance with major industry standards including ASME B18.3, RoHS 3, and REACH, guaranteeing safety and regulatory adherence.

Professional Applications & Engineering Value

This 1/4"-28 UNF Class 3A Rounded Head Screw is engineered to address critical challenges in precision assembly and corrosive settings. The 18-8 Stainless Steel material, combined with a passivated finish, provides excellent resistance to oxidation and chemical exposure, making it ideal for marine, food processing, and outdoor equipment. The fine UNF thread and Class 3A fit deliver superior clamping force and fatigue resistance, preventing loosening under dynamic loads. With a hex drive and rounded button head, installation is swift and secure, even in confined spaces. These screws are widely used in machinery, electronic enclosures, and automotive subsystems where corrosion resistance, high tensile strength, and dimensional accuracy are paramount for operational safety and longevity.

Specification Summary & Compliance

This screw meets precise dimensional and performance criteria, including a Class 3A thread fit per UNF standards, ensuring tight tolerances and reliable engagement. Manufacturing adheres to ASME B18.3 specifications, with full threading over the 1-3/8" length. The product is confirmed RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, affirming the absence of hazardous substances and supporting environmental and workplace safety protocols.