S-99355A317 1/4"-20 x 1 1/4" ASME B18.3 Tamper-Resistant Asymmetrical-Drive Stainless Steel Button Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction, ideal for harsh industrial environments
• Exceptional mechanical strength with 70,000 psi tensile strength and Rockwell B70 hardness for reliable load-bearing performance
• Secure fastening through fully threaded UNC coarse thread design with Class 2A fit for consistent engagement
• Enhanced installation efficiency with asymmetrical drive style that reduces cam-out and improves torque transfer
• Reduced surface protrusion with rounded button head profile for cleaner aesthetics and improved safety
• Broad industry compatibility meeting ASME B18.3 specifications for standardized applications
• Environmental compliance with RoHS 3 and REACH regulations for global market acceptance

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these 1/4-20 UNC rounded head screws deliver exceptional performance where corrosion resistance and mechanical reliability are critical. The 18-8 stainless steel construction provides excellent protection against rust and chemical exposure in manufacturing, marine, and food processing environments. The fully threaded coarse UNC thread ensures maximum grip strength in various materials, while the asymmetrical drive style minimizes stripping during high-torque installation. With their rounded button head profile, these screws offer a low-profile solution that reduces snagging hazards and provides a finished appearance. Ideal for machinery assembly, equipment maintenance, and structural applications requiring ASME B18.3 compliance and consistent fastening performance.

Specification Summary & Compliance

This 1/4-20 UNC rounded head screw features precise Class 2A thread fit with coarse thread spacing for reliable engagement. Manufactured to ASME B18.3 standards with full compliance to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The inch-system specifications include 1-1/4" length, 0.437" head diameter, and U25 drive size, ensuring dimensional accuracy and interchangeability across industrial applications.