S-91035A210 4-40 x 1/2" ASTM A581, ASTM A582 Captive Panel Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction for long-lasting performance in harsh industrial environments
• Excellent grip and easy manual operation thanks to the knurled round head design, eliminating the need for tools in many applications
• Secure captive panel retention with partially threaded shank that prevents the screw from falling out during assembly or disassembly
• Reliable coarse threading with 4-40 UNC specification and Class 2A fit for quick installation and consistent engagement
• Dual drive compatibility featuring both thumb operation and slotted drive for flexible installation methods
• Compliance with industry standards including ASTM A581 for material quality and RoHS 3/REACH for environmental safety
• Right-hand thread direction for standard installation procedures familiar to maintenance personnel

Professional Applications & Engineering Value

This 4-40 UNC thumb screw delivers exceptional engineering value in captive panel applications where reliability and corrosion resistance are paramount. The 18-8 stainless steel construction provides superior protection against rust and chemical exposure, making it ideal for electronics enclosures, industrial control panels, and medical equipment. The knurled head texture ensures positive grip even with gloved hands, while the partially threaded design maintains screw retention during panel maintenance. The coarse UNC threading offers faster installation and reduced cross-threading risks compared to fine-thread alternatives. These features combine to create a captive panel fastener that withstands vibration, frequent access cycles, and demanding environmental conditions without compromising performance.

Specification Summary & Compliance

This thumb screw features precision 4-40 UNC coarse threading with Class 2A fit tolerance for reliable engagement and consistent performance. The fastener meets ASTM A581 material specifications for quality assurance and is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant for environmental safety. With a 1/2" overall length and 1/8" thread length, the partially threaded design ensures optimal captive panel functionality while maintaining structural integrity across various industrial applications.