S-99355A311 1/4"-20 x 3/4" 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 for long-lasting performance in harsh environments
• Exceptional holding power from 70,000 psi tensile strength and Rockwell B70 hardness for reliable fastening in demanding applications
• Quick and secure installation with coarse UNC threading and Class 2A fit ensuring consistent engagement and reduced cross-threading risk
• Enhanced torque transmission through asymmetrical U25 drive design for improved tool engagement and reduced cam-out
• Streamlined assembly process with fully threaded design providing maximum thread contact along the entire shank length
• Regulatory compliance assurance meeting ASME B18.3 standards, RoHS 3, and REACH for quality and environmental safety
• Low-profile rounded head design offering smooth finished appearance while maintaining structural integrity

Professional Applications & Engineering Value

These 18-8 stainless steel rounded head screws deliver critical engineering advantages in industrial settings where corrosion resistance and mechanical strength are paramount. The coarse UNC threading with Class 2A fit ensures rapid installation in various materials while maintaining precise dimensional accuracy. The asymmetrical U25 drive system provides superior torque transmission, reducing fastener damage during high-torque applications. With full threading along the 3/4" length, these screws maximize load distribution in assemblies subjected to vibration and dynamic stresses. Ideal for machinery, equipment manufacturing, and structural applications, these fasteners solve common challenges of fastener failure, corrosion-induced degradation, and installation inefficiency in demanding industrial environments.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread fit tolerances with UNC coarse threading (1/4"-20) for consistent performance. Complies with ASME B18.3 dimensional standards and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features right-hand thread direction and fully threaded design with precise 0.25" thread diameter and standardized button head profile for uniform installation characteristics across production runs.