S-91900A912 4-40 x 1" ASME B18.3 Tamper-Resistant Torx Stainless Steel Button Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized Torx T8 drive that deters unauthorized access while providing secure installation
• Superior corrosion protection through 18-8 stainless steel construction and passivated surface treatment for extended service life
• Precise thread engagement with Class 3A thread fit ensuring reliable fastening in critical applications
• Optimized head design featuring rounded button profile that reduces surface protrusion while maintaining structural integrity
• High mechanical performance delivering 70,000 psi tensile strength and Rockwell B70 hardness for demanding environments
• Full-threaded construction providing maximum grip length and uniform stress distribution along the entire 1" shaft
• Regulatory compliance assurance meeting ASME B18.3 specifications while being RoHS 3 and REACH compliant

Professional Applications & Engineering Value

These 4-40 UNC thread screws with tamper-resistant Torx T8 drive address critical security requirements in industrial assemblies where unauthorized access prevention is paramount. The 18-8 stainless steel composition combined with passivated finish creates a robust barrier against corrosive elements in harsh environments, from outdoor enclosures to chemical processing equipment. The Class 3A thread fit ensures precise mating with corresponding nuts and threaded holes, eliminating play and vibration-induced loosening in precision machinery. The rounded button head design provides a low-profile installation ideal for applications with clearance constraints while maintaining sufficient bearing surface. These fully threaded security screws deliver consistent clamping force across the entire 1" length, making them particularly valuable in electronic enclosures, access panels, and public infrastructure where both security and durability are engineering priorities.

Specification Summary & Compliance

Manufactured to exacting ASME B18.3 specifications with Class 3A thread fit precision and UNC coarse thread spacing for reliable engagement. The 4-40 thread size with 0.112" diameter and right-hand thread direction follows industry standards. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations ensures environmental responsibility. Mechanical properties include Rockwell B70 hardness and 70,000 psi tensile strength for demanding applications.