S-91870A110 4-40 x 1/4" ASME B18.3 Tamper-Resistant Torx Stainless Steel Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized Torx T8 drive for secure installations in high-security environments
• Superior corrosion protection from passivated 18-8 stainless steel construction, ideal for harsh industrial conditions
• Reliable mechanical performance with 70,000 psi tensile strength and Rockwell B70 hardness for demanding applications
• Optimized flush mounting featuring undercut flat head design with 82° countersink angle for seamless surface integration
• Consistent thread engagement through full UNC coarse threading with Class 2A fit for vibration-resistant fastening
• Broad regulatory compliance meeting ASME B18.3 standards and environmental regulations including RoHS 3 and REACH
• Versatile right-hand threading compatible with standard 4-40 UNC components across multiple industries

Professional Applications & Engineering Value

These tamper-resistant Torx flat head screws address critical security and durability challenges in industrial applications. The 18-8 stainless steel base material combined with passivated finish creates exceptional resistance to corrosion and chemical exposure, making them ideal for electronics enclosures, medical devices, and outdoor equipment. The specialized T8 drive system prevents unauthorized access while the undercut flat head profile ensures flush mounting without protrusion. With full UNC coarse threading and Class 2A thread fit, these screws maintain secure fastening in high-vibration environments, while the 82° countersink angle provides optimal load distribution. The combination of 70,000 psi tensile strength and Rockwell B70 hardness ensures long-term reliability in mechanical assemblies where tampering prevention and environmental resistance are paramount.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with 4-40 UNC coarse thread specifications. Complies with ASME B18.3 mechanical standards and meets environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance. Features include 0.225" head diameter, 1/4" length, right-hand thread direction, and fully threaded design. The passivated finish on 18-8 stainless steel provides enhanced surface protection while maintaining the material's inherent corrosion resistance properties.