S-99355A305 1/4"-20 x 1/2" 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 environments and reducing replacement frequency
• High tensile strength of 70,000 psi ensures reliable performance under significant mechanical stress and vibration
• Rockwell B70 hardness provides excellent wear resistance and maintains thread integrity over repeated use
• Class 2A thread fit offers smooth assembly and reliable engagement, minimizing cross-threading risks in production lines
• Fully threaded 1/4"-20 UNC coarse design delivers maximum grip and faster installation in a wide range of materials
• Rounded (button) head with asymmetrical U25 drive reduces cam-out and provides a clean, low-profile finish for aesthetic and safety-critical applications
• Compliance with ASME B18.3, RoHS 3, and REACH guarantees consistent quality and environmental safety for global industrial supply chains

Professional Applications & Engineering Value

Engineered for demanding industrial environments, this 18-8 stainless steel rounded head screw combines material durability with precision UNC coarse threading to address common assembly challenges. Its 70,000 psi tensile strength and Rockwell B70 hardness prevent stripping and deformation in high-vibration machinery, automotive components, and electronic enclosures. The fully threaded 1/4"-20 design ensures uniform load distribution, while the asymmetrical U25 drive enhances torque transfer efficiency, reducing installation time and tool wear. Ideal for OEM manufacturing, maintenance repairs, and outdoor equipment, this screw offers long-term reliability where corrosion resistance and ASME B18.3 compliance are critical for operational safety and reduced downtime.

Specification Summary & Compliance

This 1/4"-20 UNC screw adheres to Class 2A thread fit tolerances for consistent assembly precision. Manufacturing follows ASME B18.3 specifications, ensuring dimensional accuracy and interchangeability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances for safe use in global markets.