Skip to main content
Home / Screws / Grade 12.9 High Strength Black Nickel Internal Hex Screw Cylinder Head Extended Screw Bolt M2.5M3M4M5M6M8

Attributes

Brand -
Category Standard Parts, Components & Industrial Consumables / Screws
Origin -
Material Grade Alloy Steel Grade 12.9
Surface Finish Black Nickel Plated
Drive Type Internal Hex (Allen)
Head Style Cylinder Head (Socket Cap)
Available Sizes M2.5, M3, M4, M5, M6, M8
Thread Pitch Standard Coarse Thread
Tensile Strength Minimum 1220 MPa
Application High-Stress Mechanical Assembly
Corrosion Resistance Moderate (Indoor Use Recommended)
Package Type Bulk Box or Individual Packs

6 reviews

A

Anonymous

Mar 28, 2026

Rating: 5/5

Perfect fit

Ordered the M5 size and they fit precisely into my pre-drilled holes. The extended length option was very helpful for my specific setup.

A

Anonymous

Mar 20, 2026

Rating: 5/5

Excellent quality for high-torque applications

These bolts are exactly what I needed for my CNC machine assembly. The Grade 12.9 rating holds up well under significant torque without stripping the hex drive.

A

Anonymous

Mar 18, 2026

Rating: 4/5

Good value, fast shipping

The black nickel finish looks professional and matches my project aesthetics. One bolt had a slightly imperfect thread, but the rest of the batch was perfect.

A

Anonymous

Mar 17, 2026

Rating: 5/5

Strong and durable

Used these for a custom bicycle frame modification. They handle the vibration and stress perfectly. Highly recommend for serious builders.

A

Anonymous

Mar 16, 2026

Rating: 5/5

Repeat purchase for a reason

I've ordered these three times now for various automotive projects. They never fail, and the consistency in sizing is impressive.

A

Anonymous

Mar 08, 2026

Rating: 4/5

Solid hardware

Very strong screws. Just make sure you use a high-quality Allen key, as cheaper tools might round off the socket if you apply too much force.

5 FAQ

Q: What is the maximum torque rating for the M6 size?

A: For an M6 Grade 12.9 bolt with standard lubrication, the recommended tightening torque is approximately 10-12 Nm. Please refer to specific engineering tables for your exact application requirements.

Q: Is the head height standard for socket cap screws?

A: Yes, our cylinder head dimensions adhere to ISO 4762 standards, ensuring compatibility with standard sockets and fittings for the respective metric sizes.

Q: Can I return unopened boxes if I ordered the wrong size?

A: Absolutely. We accept returns on unopened packaging within 30 days of delivery. Please initiate a return request through your order history page.

Q: Are these screws suitable for outdoor use in rainy conditions?

A: While the black nickel plating offers some protection, Grade 12.9 alloy steel is prone to rust in prolonged wet environments. We recommend using them indoors or applying additional corrosion protection for outdoor use.

Q: Do you sell matching washers for these bolts?

A: Yes, we carry hardened steel washers compatible with Grade 12.9 fasteners. Please search our store for 'Grade 12.9 Washers' to find the matching sizes for your order.

Explore your interests

All Categories
Best Seller (30)
New List (30)
Maike Outdoor Sports Waterproof Backpack Wet-Dry Separation Ski Bag Fishing Creek Fins Multi-Function Gear Storage

Maike Outdoor Sports Waterproof Backpack Wet-Dry Separation Ski Bag Fishing Creek Fins Multi-Function Gear Storage

$152.00

Viral NFC Chip Stickers for Music Wall - Adhesive Read/Write Tags for Song Scanning, Cards, and Photo Frames

Viral NFC Chip Stickers for Music Wall - Adhesive Read/Write Tags for Song Scanning, Cards, and Photo Frames

$2.38

Rechargeable Generation 2 Personal Air Purifier - Safe Portable Electric Fan for Travel Commuting and Flights

Rechargeable Generation 2 Personal Air Purifier - Safe Portable Electric Fan for Travel Commuting and Flights

$181.00

Integrated Sink Splash Guard with Silicone Drain Mat - Auto-Draining Countertop Organizer

Integrated Sink Splash Guard with Silicone Drain Mat - Auto-Draining Countertop Organizer

$23.30

Ultra-Light Aluminum Camping Light Pole – Foldable Mini Lamp Stand for Outdoor Picnics and Tabletop Use

Ultra-Light Aluminum Camping Light Pole – Foldable Mini Lamp Stand for Outdoor Picnics and Tabletop Use

$8.33

bimoz Under-Desk Cable Organizer No-Drill Shelf for Home Office Socket Strip Router Wire Data Cable Fixer Minimalist Wire Winder Dual-Side Mount Ventilated Design

bimoz Under-Desk Cable Organizer No-Drill Shelf for Home Office Socket Strip Router Wire Data Cable Fixer Minimalist Wire Winder Dual-Side Mount Ventilated Design

$40.80

Extended Deep-Cut External Thread Tool Holder with Relief Groove for Swiss-Type Lathe HKFF42R6001

Extended Deep-Cut External Thread Tool Holder with Relief Groove for Swiss-Type Lathe HKFF42R6001

$15.50

Meiao Dental Imported Dental Implant Package, Swiss ITI Straumann Implant Abutment, False Teeth, Filling, and Planting

Meiao Dental Imported Dental Implant Package, Swiss ITI Straumann Implant Abutment, False Teeth, Filling, and Planting

$14,188.00

Assorted Colors Kids' Painting Crayons - Washable Oil Pastels in 12, 18, 24, or 36 Colors for Graffiti and Coloring

Assorted Colors Kids' Painting Crayons - Washable Oil Pastels in 12, 18, 24, or 36 Colors for Graffiti and Coloring

$2.47

Fruit and Vegetable Slicer - Stainless Steel Commercial Electric Multi-Function Shredder for Radish, Potato, Cucumber, Pepper, Automatic

Fruit and Vegetable Slicer - Stainless Steel Commercial Electric Multi-Function Shredder for Radish, Potato, Cucumber, Pepper, Automatic

$2,880.00

CAAS-Developed Granular Insecticide and Fungicide for Vegetable Gardens – Soil Pest Control and Fertilizer for Enhanced Vegetable Growth and Yield

CAAS-Developed Granular Insecticide and Fungicide for Vegetable Gardens – Soil Pest Control and Fertilizer for Enhanced Vegetable Growth and Yield

$13.50

Marie's C6823 Sketch Blending Stumps (3-Pack), Professional Charcoal and Pastel Smudging Tools for Art Students and Beginners, Hard/Small/Highlight Set on Newsprint

Marie's C6823 Sketch Blending Stumps (3-Pack), Professional Charcoal and Pastel Smudging Tools for Art Students and Beginners, Hard/Small/Highlight Set on Newsprint

$7.48

Inverted Water Dispenser Stand with Manual Pump for Large Mineral Water Bottles

Inverted Water Dispenser Stand with Manual Pump for Large Mineral Water Bottles

$67.00

Lanzhai Flagship Store Multifunctional Retro Brush Washer Set, Creative Ceramic Large National Painting Tea Rinse Bowl, Art Display Paperweight, Student Calligraphy Supplies

Lanzhai Flagship Store Multifunctional Retro Brush Washer Set, Creative Ceramic Large National Painting Tea Rinse Bowl, Art Display Paperweight, Student Calligraphy Supplies

$8.42

Multi-Function Vanity Shelf Over Toilet - Floor-Standing Thickened Plastic Storage Cabinet for Squat Toilet Gaps

Multi-Function Vanity Shelf Over Toilet - Floor-Standing Thickened Plastic Storage Cabinet for Squat Toilet Gaps

$52.49

100% Cotton Watercolor Paper Pad 300gsm - Cold/Hot Press, 8K/16K/32K Sizes, Glued on Four Sides for Academy & Portable Sketching

100% Cotton Watercolor Paper Pad 300gsm - Cold/Hot Press, 8K/16K/32K Sizes, Glued on Four Sides for Academy & Portable Sketching

$11.90

Commercial Large Shredding Machine Tornado Potato Slicer Wavy Slice Equipment Carrot Slicer Multi-Function

Commercial Large Shredding Machine Tornado Potato Slicer Wavy Slice Equipment Carrot Slicer Multi-Function

$20,000.00

Electric Heating Pasteurization Tank – Horizontal Spray Type for Fresh Milk and Food Sterilization

Electric Heating Pasteurization Tank – Horizontal Spray Type for Fresh Milk and Food Sterilization

$11,211.00

[First Batch Deposit] Spring Cherry & Pear Snow - Original Lolita Ballet-Style Cake Dress Chinese JSK

[First Batch Deposit] Spring Cherry & Pear Snow - Original Lolita Ballet-Style Cake Dress Chinese JSK

$5.00

Bottled Water Electric Pump Bracket, Mineral and Pure Water Dispenser, Automatic Water Outlet Device

Bottled Water Electric Pump Bracket, Mineral and Pure Water Dispenser, Automatic Water Outlet Device

$383.98

Micro-Hyperbaric Oxygen Chamber - Rigid Sit/Lie Model for Home and Commercial Use, High-Altitude Oxygen Therapy Room

Micro-Hyperbaric Oxygen Chamber - Rigid Sit/Lie Model for Home and Commercial Use, High-Altitude Oxygen Therapy Room

$150.00

Stainless Steel Illuminated Hotel Room Number Plate, Smart Electronic Door Sign with Do Not Disturb and Make Up Room Bell

Stainless Steel Illuminated Hotel Room Number Plate, Smart Electronic Door Sign with Do Not Disturb and Make Up Room Bell

$10.00

Paper Blending Stump A1zdq001 - Large Art Sketch Highlighting Tool for Students

Paper Blending Stump A1zdq001 - Large Art Sketch Highlighting Tool for Students

$4.15

Continental Run-Flat Tires 225 235 245 255 265/45 50 55R17R18R19R20R21R22

Continental Run-Flat Tires 225 235 245 255 265/45 50 55R17R18R19R20R21R22

$350.00

3D Printing Pen for Children - 3D Stereoscopic Drawing Toy for Boys and Girls (Ages 6+)

3D Printing Pen for Children - 3D Stereoscopic Drawing Toy for Boys and Girls (Ages 6+)

$35.70

MOOCAT Loose-Leaf Refill – 300G Wood Pulp Fine-Texture Blank Paper for OC Binders A9/B5/M5/M6 Hand Drawing

MOOCAT Loose-Leaf Refill – 300G Wood Pulp Fine-Texture Blank Paper for OC Binders A9/B5/M5/M6 Hand Drawing

$12.90

Lanzhai Calligraphy Wool Felt Mat – Mini Arm Rest and Inkstone Pad with Creative Chinese Style Design for Painting and Writing

Lanzhai Calligraphy Wool Felt Mat – Mini Arm Rest and Inkstone Pad with Creative Chinese Style Design for Painting and Writing

$7.48

Qing Dynasty Calligrapher Lin Zexu Guangeti Small Regular Script: Buddha Speaks of the Infinite Life Sutra, Brush Tracing Practice Long Scroll Copybook

Qing Dynasty Calligrapher Lin Zexu Guangeti Small Regular Script: Buddha Speaks of the Infinite Life Sutra, Brush Tracing Practice Long Scroll Copybook

$8.80

Lightweight Ceramsite Bottom Padding, Professional Backfill for Sunken Bathroom Engineering and Construction, Large Granules

Lightweight Ceramsite Bottom Padding, Professional Backfill for Sunken Bathroom Engineering and Construction, Large Granules

$30.10

[In Stock] MINISO YOYO Wind-Chasing Diary Series Aromatherapy Figure Blind Box – Youyou-chan Ornament

[In Stock] MINISO YOYO Wind-Chasing Diary Series Aromatherapy Figure Blind Box – Youyou-chan Ornament

$49.00