S-91253A102 4-40 x 1/8" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating for extended service life in demanding environments
• Superior thread engagement with Class 3A fit ensuring precise, vibration-resistant connections
• Maximum drive torque capability through hex drive design preventing tool slippage during installation
• Enhanced flush mounting with 82° undercut flat head profile for seamless surface integration
• Reliable high-strength performance with 130,000 psi tensile strength and Rockwell C39 hardness
• Full thread coverage along the entire 1/8" length for optimal load distribution
• Regulatory compliance assurance meeting ASTM F835, RoHS 3, and REACH environmental standards

Professional Applications & Engineering Value

These 4-40 UNC flat head screws with black-oxide alloy steel construction address critical industrial fastening challenges where space constraints and corrosion resistance are paramount. The undercut flat head profile with 82° countersink enables perfect flush mounting in precision assemblies, while the Class 3A thread fit provides superior vibration resistance in machinery and equipment. The hex drive design ensures secure installation without cam-out, making them ideal for aerospace components, electronic enclosures, and automotive systems requiring reliable high-tensile strength fasteners. The combination of fully threaded construction and coarse thread spacing delivers rapid assembly and maximum holding power in thin-section materials.

Specification Summary & Compliance

Manufactured to exacting UNC thread standards with Class 3A thread fit for precision applications. Compliant with ASTM F835 specifications for mechanical properties and performance. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features right-hand thread orientation with coarse thread spacing for optimal engagement in various materials.