S-91900A110 4-40 x 1/2" 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, preventing unauthorized access in secure environments.
• Superior corrosion resistance from 18-8 stainless steel and passivated finish, ensuring longevity in harsh industrial conditions.
• High mechanical strength with 70,000 psi tensile strength and Rockwell B70 hardness for reliable performance under stress.
• Precise thread engagement with Class 3A fit and coarse UNC threading, enabling quick installation and vibration resistance.
• Secure rounded button head design reduces snagging risks while providing a low-profile, aesthetically clean finish.
• Full regulatory compliance with ASME B18.3, RoHS 3, and REACH, ensuring safety and environmental standards are met.
• Versatile right-hand threading with full-length threads for consistent fastening across various materials.

Professional Applications & Engineering Value

Engineered for high-security and demanding industrial settings, these 4-40 UNC threaded screws address critical challenges like vandalism, corrosion, and mechanical failure. The 18-8 stainless steel construction, combined with a passivated finish, provides exceptional resistance to moisture, chemicals, and oxidation—ideal for outdoor equipment, electronic enclosures, and machinery exposed to harsh environments. The tamper-resistant Torx T8 drive ensures that fasteners remain secure in public or restricted areas, reducing maintenance costs and unauthorized tampering. With a coarse thread spacing and Class 3A fit, these screws offer rapid installation and reliable hold in metals and plastics, streamlining assembly processes while meeting rigorous ASME B18.3 specifications for consistency and safety.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including UNC 4-40 thread size with Class 3A thread fit for tight tolerances and optimal performance. Manufacturing follows ASME B18.3 specifications, ensuring uniformity and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances and supporting environmentally responsible sourcing for global industrial applications.