10-Pack UNC Flat Head Hex Socket Screws – 10.9 Grade Steel

10-Pack UNC Countersunk Hex Socket Screws – 10.9 Grade Carbon Steel

Upgrade your fastening game with these 10.9 Grade High-Strength Countersunk Hex Socket Screws. Available in Anglo-American standard sizes (UNC), these flat-head Allen bolts are precision-engineered to sit flush with any surface — ideal for clean, professional assemblies in mechanical, electronic, and DIY projects.

Key Features

• Grade 10.9 High-Strength Carbon Steel – Built to handle demanding torque and load requirements without stripping or deforming.
• Countersunk Flat Head – Sits perfectly flush with your workpiece for a neat, snag-free finish.
• Hex Socket (Allen Key) Drive – Provides superior torque transfer and reduces cam-out compared to standard Phillips or slotted heads.
• Blackened Surface Treatment – Adds a layer of corrosion resistance and a sleek, professional appearance.
• UNC Thread Standard – Compatible with Anglo-American standard sizing: 4#-40, 6#-32, 8#-32, 10#-32, 10#-24.
• Pack of 10 – Great for repairs, prototyping, or keeping as workshop spares.

Specifications

Size Reference Guide

Thread size notation explained: 4#-40 × 3/16 means — Thread Diameter: #4 inch | Threads Per Inch: 40 | Thread Length: 3/16 inch. Select your required size combination from the available options at checkout.

Perfect For

• Electronics enclosures and chassis assembly
• Mechanical fabrication and machine building
• Woodworking jigs and fixtures
• Workshop repairs and prototyping
• Any application requiring a flush-mount fastener

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Frequently Asked Questions

Q: What sizes are included in these UNC countersunk hex socket screws?

A: These screws are available in Anglo-American UNC standard sizes: 4#-40, 6#-32, 8#-32, 10#-32, and 10#-24. Each pack contains 10 pieces of the selected size. The notation includes thread diameter, threads per inch, and optional thread length (e.g., 4#-40 × 3/16).

Q: What tool do I need to drive these hex socket screws?

A: These screws require an Allen key (hex key) or hex socket bit. The specific hex key size depends on the screw size selected — refer to standard UNC hex socket specifications for the appropriate key size for each thread diameter.

Q: Are these screws suitable for metal-to-metal fastening?

A: Yes. The 10.9 grade carbon steel construction makes these screws well-suited for metal-to-metal, metal-to-plastic, and similar demanding fastening applications. The blackened surface treatment also provides added durability and mild corrosion resistance.

Q: What does the flat/countersunk head design offer over other head styles?

A: The countersunk flat head sits flush with or below the surface of the material once fully driven, eliminating protruding bolt heads. This is ideal for applications where a smooth, snag-free surface is required, such as panels, enclosures, and precision machinery.

Production & Packaging Notice

To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.