10pcs Grade 10.9 Hex Countersunk Flat Head Screws British Standard

JARBLUE Grade 10.9 British Standard Hex Socket Countersunk Flat Head Screws – 10-Pack

Upgrade your metalworking and DIY projects with these Grade 10.9 Carbon Steel Hex Socket Countersunk Flat Head Screws from JARBLUE. Engineered to British Standard specifications, these high-strength machine screws deliver exceptional holding power, a flush-fitting profile, and reliable performance across a wide range of applications — from mechanical assemblies to structural fabrication.

Whether you're working on automotive builds, precision engineering, or heavy-duty joinery, these flat head bolts sit perfectly flush with the material surface for a clean, professional finish. Available in six British Standard thread sizes to suit your exact requirements.

Available Thread Sizes

• T1: 1/4 – 20
• T2: 1/8 – 40
• T3: 3/16 – 24
• T4: 3/8 – 16
• T5: 5/16 – 18
• T6: 5/32 – 32

Key Specifications

• Brand: JARBLUE
• Material: Grade 10.9 Carbon Steel
• Standard: British Standard (BSW / BSF)
• Drive Style: Hex Socket
• Head Style: Flat (Countersunk)
• Screw Type: Machine Screws
• Certification: CE
• Package Quantity: 10 Pieces
• Country of Origin: Made in China

Why Choose These Screws?

• ✅ High Strength Grade 10.9 – Superior tensile strength for demanding applications
• ✅ Flush Finish – Countersunk flat head sits level with the surface, ideal for tight clearances
• ✅ British Standard Thread – Compatible with standard BSW/BSF tapped holes
• ✅ Carbon Steel Construction – Excellent durability and resistance to shear forces
• ✅ Hex Socket Drive – Allows high torque application with an Allen/hex key
• ✅ CE Certified – Meets recognized quality and safety standards
• ✅ Versatile Sizing – Six thread size options to cover multiple project needs

Ideal Applications

• Mechanical and structural assemblies
• Automotive and machinery fabrication
• Metalworking and engineering projects
• Furniture and joinery with flush-fit requirements
• General DIY and repair work

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Learn more: OSHA guidance on hand and power tools

Frequently Asked Questions

Q: What does "Grade 10.9" mean for these hex countersunk screws?

A: Grade 10.9 refers to the mechanical strength classification of the carbon steel used. It indicates a minimum tensile strength of approximately 1040 MPa (1040 N/mm²), making these screws suitable for high-stress mechanical and structural fastening applications where a standard-grade screw would not provide sufficient holding power.

Q: What British Standard thread specifications do these flat head screws follow?

A: These screws are manufactured to British Standard thread specifications (BSW/BSF). The six available size variants cover thread pitches from 1/8-40 up to 3/8-16, making them compatible with standard British Standard tapped holes and nuts used in a wide range of engineering and mechanical contexts.

Q: What size hex key (Allen key) do I need to drive these screws?

A: The exact hex key size will vary depending on the thread size selected (T1–T6). As a general guide, larger diameter screws (e.g. 3/8") require larger hex keys. Please refer to a standard British Standard hex socket chart to match the correct Allen key size to your chosen screw variant before installation.

Q: Are these screws suitable for outdoor or high-moisture environments?

A: These screws are made from carbon steel, which offers excellent strength but is not inherently corrosion-resistant. For outdoor or high-humidity environments, we recommend using them with a suitable protective coating or sealant to extend service life.

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.