S-91900A111 4-40 x 3/4" ASME B18.3 Tamper-Resistant Torx Stainless Steel Button Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized T8 Torx 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 in harsh environments
• Reliable high-strength performance with 70,000 psi tensile strength and Rockwell B70 hardness to withstand demanding mechanical loads
• Precision thread engagement featuring Class 3A thread fit and full UNC coarse threading for secure fastening in various materials
• Optimized head design with rounded button profile providing a finished appearance while minimizing snagging hazards
• Regulatory compliance assurance meeting ASME B18.3 specifications and environmental standards for industrial applications
• Versatile installation capability with right-hand threading and coarse thread spacing for efficient driving in multiple substrates

Professional Applications & Engineering Value

This 18-8 stainless steel tamper-resistant screw addresses critical security and durability challenges in industrial settings. The combination of passivated finish and stainless steel material provides exceptional corrosion resistance for applications exposed to moisture, chemicals, or outdoor elements. The specialized T8 Torx drive design prevents tampering in public access equipment, security panels, and regulated enclosures while maintaining installation efficiency. With Class 3A thread fit and coarse UNC threading, these fasteners deliver reliable performance in metal assemblies, electronic enclosures, and machinery where vibration resistance and security are paramount. The rounded head profile offers both aesthetic appeal and safety by eliminating sharp edges in consumer-facing applications.

Specification Summary & Compliance

This fastener maintains precision Class 3A thread fit per UNC standards with 4-40 thread size and coarse thread spacing. Manufacturing complies with ASME B18.3 specifications for dimensional accuracy and performance. The product meets RoHS 3 (2015/863/EU) compliance for restricted substances and REACH (EC 1907/2006) regulations regarding chemical safety. Full 3/4" length with complete threading ensures consistent engagement depth across applications.