S-99926A102 4-40 x 1/4" 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 mechanical strength with 70,000 psi tensile strength and Rockwell B70 hardness for reliable performance under high stress
• Precise thread engagement with Class 3A thread fit ensuring secure fastening and vibration resistance in critical assemblies
• Optimized flush mounting featuring a 100° countersink angle and undercut flat head profile for seamless surface integration
• Efficient installation with hex drive design and 1/16" drive size enabling quick assembly with standard tools
• Enhanced durability through coarse UNC threading and partial threading design providing optimal grip in various materials
• Regulatory compliance meeting RoHS 3 and REACH standards for safe use in global industrial applications

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these 4-40 UNC flat head screws deliver critical performance advantages where material integrity and precision matter. The 18-8 stainless steel composition combined with passivated finish provides exceptional resistance to corrosion, oxidation, and chemical exposure, making them ideal for electronics enclosures, machinery panels, and outdoor equipment. The Class 3A thread fit ensures tighter tolerances than standard fasteners, preventing loosening in high-vibration applications while the 100° countersink angle and undercut head profile create a flush surface finish that eliminates protrusions in precision assemblies. With 70,000 psi tensile strength, these hex drive screws maintain structural integrity in load-bearing applications across aerospace, automotive, and industrial manufacturing sectors.

Specification Summary & Compliance

This 4-40 UNC flat head screw features precision Class 3A thread fit with coarse thread spacing and right-hand threading. Manufactured to exact dimensional specifications including 1/4" length, 0.255" head diameter, and 0.18" minimum thread length. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe usage in global industrial markets. The partially threaded design and 100° countersink angle meet industry standards for flush-mounted applications requiring reliable fastening performance.