Attributes

Brand	-
Category	Industrial Small Parts / Connectors and Fasteners
Origin	-
Material	Alloy Steel
Strength Grade	12.9
Surface Finish	Black Oxide
Head Type	Socket Cap Head
Drive Type	Hex Socket (Inner Hex)
Thread Standard	Metric Coarse
Available Sizes	M3, M4, M5, M6, M8
Hardness	HRC 39-44
Special Feature	Knurled Under Head
Manufacturing Standard	DIN 912 / ISO 4762

5 reviews

Anonymous

Apr 24, 2026

Rating: 5/5

Excellent strength for machinery

Used these 12.9 grade screws for a custom engine mount. The hardness is genuine and they did not strip under high torque. The black oxide finish looks professional too.

Anonymous

Mar 24, 2026

Rating: 4/5

Good value bulk pack

Great quality for the price. Only giving 4 stars because the hex key needed was not included, but the bolts themselves are top notch hardened steel.

Anonymous

Mar 14, 2026

Rating: 5/5

Perfect fit for M5 projects

Ordered the M5 size for my 3D printer frame. The threads are clean and the knurled head helps prevent loosening due to vibration. Highly recommended.

Anonymous

Feb 16, 2026

Rating: 5/5

Exactly as described

Needed extended length bolts for a thick assembly. These reinforced bolts handled the load without bending. Fast shipping and well packaged.

Anonymous

Feb 14, 2026

Rating: 5/5

High quality finish

The black oxide coating is even and provides decent corrosion resistance for indoor use. The cup head sits flush as expected. Will buy again.

5 FAQ

Q: Are these screws rust-proof for outdoor use?

A: The black oxide finish provides mild corrosion resistance. For harsh outdoor environments, we recommend applying additional grease or using stainless steel alternatives.

Q: Do you offer bulk discounts for over 1000 units?

A: Yes, we offer tiered pricing for bulk orders. Please contact our sales team directly through the store page for a custom quote.

Q: What is the recommended torque for the M6 size?

A: For Grade 12.9 M6 bolts, the typical torque specification is around 10-12 Nm, but please consult a torque chart for your specific application and lubrication conditions.

Q: Can these be used with aluminum parts?

A: Yes, but be cautious of galvanic corrosion between steel and aluminum. Using an anti-seize compound is advised to prevent seizing and corrosion.

Q: Is the thread length full or partial?

A: These are fully threaded bolts across all available sizes (M3 to M8), ensuring maximum grip length for your assembly.

Explore your interests

Japan BPJ Imported Deep Groove Ball Bearings 6006 6007 6008 6009 6010 6011 ZZ RS P4

$23.31

PNY8LMK10 12 13 16 20 25 30 35 40LUU50 Extended Square Flange Linear Bearing Imported

$37.00

45# Medium Carbon Steel Straight Guide Bushing: Inner Diameter D10-D50, Shoulderless Straight Liner, Bushing, Steel Sleeve

$1.00

Heavy-Duty Galvanized Double Round Clamps for Utility Poles, Street Light Poles, Iron/Steel Pipes, Cable Flat Bar Fasteners

$28.00

304 Stainless Steel Hex Socket Screw Cup Head Bolt Cylinder Head Extended M2 M2.5 M3 M4 M5 M6 M8 M10mm

$1.43

German Imported YLV 304 Stainless Steel Corrosion-Resistant Bearings S6800/6801/6802/6803/6804/6805

$5.80

PTFE (Teflon) Fully Threaded Studs, Double-Ended Internal/External Hex Screws, Nuts, Bolts, Washers, and Spring Washers

$4.50

T-Shaped Rubber Hexagonal Spider Coupling Elastic Block Polyurethane Buffer Pad Water Pump Shock Absorber Toughened Hex Pad

$5.00

Stainless Steel Bushings (Inner Dia: 2/2.5mm, Outer Dia: 4/5/6mm), Steel Guide Sleeves, Wear-Resistant Liners, Miniature Spacers

$2.00

Black 304 Stainless Steel Hex Nut, Flat Washer, and Spring Washer Kit M3-M10

$2.70

[M2-M20] Stainless Steel Spring Washer

$0.76

Aluminum Alloy Spider Coupling Star Leadscrew Encoder High Torque Ball Screw Servo Motor Coupling

$1.62

Grille Panel Invisible Fastener, Grille Strip Sliding Groove, Cabinet Top Line Connector, Roman Column Decorative Woodworking Clip Connection

$5.80

Black 304 Stainless Steel Smooth Cup Head Socket Screw, Unknurled Cylinder Bolt M2 M3 M4 M5 M6 M8

$3.50

Imported Extended Square Flange Linear Bearing Electroplated Rust-Resistant LMK8 10 16 20 25 30 35 40LUU

$12.20

Linear Shaft Guide Box-Type Slider Linear Bearing Steel Retainer Bronze Bushing SC8 12 13 16 22 53 35 45 0UU

$3.80

Guide Shaft Support Open-Type Flange Bearing Housing STHWRB Smooth Shaft Fixed Support GBJ Series Shaft Support

$11.00

Hardened Bearing Steel Bushing, Wear-Resistant Liner, High-Precision Guide Sleeve, Collar, and Spacer Set

$3.69

Imported Bearing Model Assortment: 6000RS, 6001 High-Speed, 6002 Motor, 6003, 6004, 6005, 6006

$2.50

25mm Round Stainless Steel Pipe Connector, Clothes Drying Rack Accessory, Display Stand Fastener, Shelf Fixing Two-Way Joint

$1.20

Miniature Ball Bearings with Shoulder Flange Catalog - Inner Diameters 2 3 4 5 6 7 8 9 10

$13.00

L-Type Jaw Coupling, Spider Coupling, High Torque, Black Oxide Finish, Free Shipping from Manufacturer

$7.00

MYT Meiyate Square Flange Linear Bearing LMK6 8 10 12 13 16 20AUU/LAUU Nickel-Plated Rust-Proof

$13.80

Extended Box-Type Slider Bearing Linear Rail SCS8 10 12 13 16 20 25 35 40 5060LUU

$6.80

304 Stainless Steel Countersunk Hex Socket Screw and Nut Set with Flat and Spring Washers

$1.29

National Standard Brass Hex Socket Screw, Nut, Bolt, and Washer Assortment Set

$8.80

304 Stainless Steel Locking Washer for Round Nuts, Six-Claw Retaining Plate, Black Iron GB858

$11.00

C&U Bearings for Automotive Alternators - SA608, 6201, 6202, 6302, 6303, 6304/2RSM/C3

$3.50

Plastic Hammer Head Nut M8 M10 Furniture Connector Embedded Fastener Hardware Accessories

$5.11

Multi-Spec Large Lubricated Copper Shaft Bushings - Centrifugal Cast Oil-Free Sleeves and Blank Bushings

$94.90

304 Stainless Steel Rivet Nuts, Aluminum Flat Head Rivnuts, Countersunk Rivet Nuts Assortment M3 M4 M5 M6 M8 M10

$0.91

Heavy-Duty Hanging Bracket for Bathroom Cabinets Wall-Mounted Floating Cupboard Hardware Fixing Fittings Corner Code Wall Connection Piece

$14.00

Assorted Screws and Nuts Kit M6 M8 M10 M12, Hex Head Screw, Nut, and Washer Combination Set

$5.69

Galvanized High-Strength Imperial Hex Flange Nuts UNC Grade 8, Anti-Slip Locking; UNF Fine Thread Nuts

$2.20

M3-M20 PVC External Hex Head Screws, Gray Insulated Bolts, Acid and Alkali Resistant Plastic Fasteners

$2.64

NSK High-Speed Imported Micro Bearings 605 606 607 608 609 ZZ Z1 Z2 Z3 Z4

$3.00

Aluminum Alloy Shaft Bushing, Washer, Tube Sleeve, Spacer Column, Casing, Flat Gasket, Retaining Ring, Aluminum Joint Sleeve M2 M3 M4 M5 M8-m12

$9.00

M18 M20 M22 M24 M27 M30 Grade 8.8 Extended Hex Head Bolt, Nut, Washer, and Stud Set

$4.32

Injection Molding Machine Parts ~ Large Pin Shaft ~ All Sizes Available ~ Steel Sleeve Matching ~ Bushing ~ Pin Shafts for All Models

$70.00

Guwanji Zinc-Plated Iron Cross Countersunk Screw, Nut, Flat Head Bolt, and Spring Washer Assortment M2-M12

$1.82