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Home / Connectors and Fasteners / Grade 12.9 High-Strength Countersunk Hex Socket Screws Flat Head Hex Bolts M3 M4 M5 M6 M8 M10 M20

Attributes

Brand -
Category Industrial Small Parts / Connectors and Fasteners
Origin -
Material Alloy Steel
Strength Grade 12.9
Head Style Countersunk Flat Head
Drive Type Hex Socket (Allen)
Thread Type Metric Coarse
Surface Finish Black Oxide
Standard DIN 7991
Available Sizes M3, M4, M5, M6, M8, M10, M20
Hardness 39-44 HRC
Package Quantity Varies by Selection

5 reviews

A

Anonymous

Apr 17, 2026

Rating: 5/5

Excellent Strength

Used these for high tension assembly on my CNC machine. No stripping and they held torque perfectly.

A

Anonymous

Apr 16, 2026

Rating: 5/5

High Quality

True 12.9 grade, tested with hardness kit. Very satisfied with the material quality.

A

Anonymous

Apr 02, 2026

Rating: 5/5

Fast Delivery

Arrived next day. Exactly what I needed for my automotive project. Will order again.

A

Anonymous

Mar 23, 2026

Rating: 5/5

Perfect Fit

Threads are clean and precise. M6 size fit exactly as expected without any cross-threading issues.

A

Anonymous

Mar 21, 2026

Rating: 4/5

Good Value

Great bolts for the price. Packaging could be better to prevent scratching during shipping.

5 FAQ

Q: Is this stainless steel?

A: No, this is alloy steel designed for high strength applications.

Q: Are these plated for rust resistance?

A: Yes, they feature a black oxide finish for mild corrosion protection.

Q: What key size is needed for M5?

A: You will typically need a 4mm Allen key for M5 screws.

Q: Do you sell M12 size?

A: Currently we stock up to M10 and M20. M12 is not available at this time.

Q: Is there a bulk discount available?

A: Yes, please contact support for orders exceeding 500 units.

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