S-91870A416 M4 x 20 mm ASTM F879M Tamper-Resistant Torx Stainless Steel Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced security and tamper resistance with specialized T20 Torx drive that deters unauthorized removal
• Superior corrosion resistance thanks to 18-8 stainless steel construction and passivated finish for long-lasting performance in harsh environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B96 hardness for reliable, heavy-duty fastening
• Optimized thread engagement through fully threaded Class 6g coarse threads ensuring secure, vibration-resistant connections
• Flush, low-profile installation with standard flat head design and 90° countersink angle for smooth surface finishes
• Regulatory compliance assurance meeting ASTM F879M specifications and environmental standards including RoHS 3 and REACH
• Precision metric sizing with M4 x 0.7 mm coarse thread pitch and 20 mm length for consistent fit in international applications

Professional Applications & Engineering Value

These M4 tamper-resistant flat head screws address critical security and durability challenges in industrial applications. The 18-8 stainless steel material combined with passivated finish provides exceptional resistance to corrosion, making them ideal for outdoor equipment, marine components, and chemical processing facilities where environmental exposure is a concern. The tamper-resistant T20 Torx drive prevents unauthorized access in public infrastructure, transportation systems, and secure enclosures. With fully threaded Class 6g metric coarse threading, these screws deliver maximum thread engagement and holding power, reducing the risk of loosening under vibration in machinery, automotive assemblies, and electronic housing. The flat head profile ensures flush mounting for safety and aesthetic requirements in consumer products and industrial equipment.

Specification Summary & Compliance

This metric flat head screw features precise M4 x 0.7 mm coarse threading with Class 6g thread fit tolerance for consistent performance. Manufacturing complies with ASTM F879M specifications for dimensional accuracy and mechanical properties. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring restricted substance compliance for international markets. The 90° countersink angle and standard flat head profile maintain proper seating in corresponding countersunk holes.