S-91035A220 4-40 x 5/8" ASTM A581, ASTM A582 Captive Panel Screws

Key Features & Benefits at a Glance

• Enhanced manual operation with knurled round head for superior grip without tools
• Corrosion-resistant performance from 18-8 stainless steel construction in demanding environments
• Secure panel retention through partially threaded design preventing accidental loosening
• Quick installation with coarse UNC threads and Class 2A fit ensuring smooth engagement
• Dual drive compatibility featuring both thumb-friendly knurling and slotted drive options
• Regulatory compliance meeting ASTM A581, RoHS 3 and REACH for global applications
• Optimized dimensions with 0.25" head diameter and 5/8" length for standard panel thicknesses

Professional Applications & Engineering Value

This 4-40 UNC thumb screw delivers exceptional value in panel mounting and electronic enclosure applications where frequent access is required. The 18-8 stainless steel construction provides reliable corrosion resistance in industrial environments, while the knurled head enables rapid tool-free adjustments. Engineered with partial threading, this captive panel screw maintains secure positioning without complete disengagement, eliminating lost hardware in critical assemblies. The coarse thread spacing and Class 2A thread fit ensure quick installation while maintaining vibration resistance, making it ideal for industrial fasteners in maintenance-heavy equipment.

Specification Summary & Compliance

Manufactured to ASTM A581 specifications with Class 2A thread fit tolerance for precision engagement. Features 4-40 UNC coarse threads with right-hand direction and partial threading up to 1/8" length. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards for global market acceptance. The knurled round head measures 0.25" diameter with slotted drive compatibility.