4-40 x 3/8 Brass Button Head Socket Cap Screw supports low-load assemblies that need a rounded button head along with electrical conductivity and non-magnetic material behavior. Compared with taller head styles, the rounded button head can reduce snag potential on panels, covers, and handled surfaces. The material is often selected when conductivity, machinability, and appearance are more relevant than the strength profile of alloy steel.

Appropriate uses include instrumentation and precision equipment, where the finished button head keeps visible fastening points smooth while the material machines cleanly. It can also fit machine covers and automation equipment, where internal hex drive access supports installation where side clearance for external tooling is limited. The internal hex drive supports socket-key installation in compact equipment without relying on an external wrenching surface.

For the 4-40 thread and 3/8 in. length, the reference head diameter is 0.201-0.213 in. and the head height is 0.051-0.059 in. Use the verified dimensions below when checking head projection, socket access, and replacement fit.

Technical Highlights

• Material: Brass
• Thread Size: 4-40
• Length: 3/8 in.
• Nominal Body Diameter: #4 (.112 in.)
• Head Diameter: 0.201-0.213 in.
• Head Height: 0.051-0.059 in.
• Hex-Key Size: 1/16 in.
• Drive Type: Internal Hex

Reference dimensions may vary slightly by manufacturer.