S-99891A125 3/8"-24 Hex Nuts

Key Features & Benefits at a Glance

• Exceptional strength and reliability with Grade 8 classification, ideal for high-stress, heavy-duty applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh environments
• Secure, vibration-resistant fastening from fine 3/8"-24 UNF left-hand threading, preventing loosening under counter-clockwise rotation
• Precise thread engagement ensured by Class 2B thread fit, reducing cross-threading and installation issues
• Easy installation and removal with standard external hex drive design, compatible with common wrench tools
• Optimized dimensional stability with 9/16" width and 21/64" height for consistent performance in assembled components
• Reliable left-hand thread solution for specialized machinery and rotating equipment requiring reverse-thread security

Professional Applications & Engineering Value

This Grade 8 steel hex nut with left-hand UNF fine threading addresses critical engineering challenges in high-vibration and rotational systems. The zinc yellow-chromate plated surface provides robust protection against corrosion, making it suitable for industrial environments exposed to moisture and chemicals. The 3/8"-24 UNF left-hand thread is engineered to maintain tension in applications where standard right-hand threads would loosen due to counter-clockwise motion, such as in rotating shafts, machinery guards, and specialized equipment. The fine thread spacing offers greater adjustment precision and superior resistance to vibrational loosening compared to coarse threads. Combined with the external hex drive and Class 2B thread fit, this nut ensures reliable, repeatable fastening in automotive, manufacturing, and heavy equipment applications where failure is not an option.

Specification Summary & Compliance

This hex nut features 3/8"-24 UNF left-hand fine threading with Class 2B thread fit for consistent engagement and reduced galling. Dimensions include 9/16" width across flats and 21/64" height. Manufactured from steel meeting Grade 8 strength requirements (approximately 150 ksi minimum tensile strength). The zinc yellow-chromate plating provides corrosion protection and complies with industry standards for finish durability. Product conforms to UNF thread standards and common industrial specifications for hex nuts, suitable for applications requiring precise, high-strength left-hand thread components.