S-99926A139 1/4"-20 x 7/8" Stainless Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish for extended service life in harsh environments
• Exceptional tensile strength rated at 70,000 PSI with Rockwell B70 hardness for reliable performance in demanding applications
• Precision thread engagement with UNC Class 3A fit ensuring secure fastening and vibration resistance
• Optimized head design featuring undercut flat profile and 100° countersink angle for flush mounting and reduced stress concentration
• Enhanced driving efficiency with 1/8" hex drive providing superior torque transmission and slip-resistant installation
• Regulatory compliance with RoHS 3 and REACH standards for environmentally responsible manufacturing
• Versatile threading configuration with right-hand coarse threads and partial threading for flexible application across various material thicknesses

Professional Applications & Engineering Value

This 18-8 stainless steel flat head screw delivers exceptional engineering value through its optimized material properties and mechanical design. The passivated finish significantly enhances corrosion resistance, making it ideal for industrial environments where moisture, chemicals, or temperature variations are concerns. The UNC Class 3A threading with coarse thread spacing provides superior holding power in various materials, while the undercut flat head profile with 100° countersink angle ensures flush installation that minimizes protrusion and improves aerodynamic or hydraulic flow characteristics. These hex drive screws are particularly valuable in machinery assembly, electrical enclosures, and structural frameworks where reliable fastening solutions must withstand vibration and dynamic loads without compromising integrity.

Specification Summary & Compliance

This high-performance fastener features precision 1/4"-20 UNC coarse threading with Class 3A thread fit for exceptional dimensional accuracy and engagement. The manufacturing adheres to strict quality standards with Rockwell B70 hardness and 70,000 PSI tensile strength verification. Regulatory compliance includes full conformance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental directives, ensuring responsible material sourcing and production processes for global industrial applications.