M2.5-M6 Button Head Socket Cap Screws Metric Allen Bolts - 100 Pack

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M2.5-M6 Button Head Socket Cap Screws Metric Allen Bolts - 100 Pack

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Size=d*L: M2.5*4mm

Package Quantity: 100

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$3.39 USD

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In stock (500 units), ready to be shipped

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Metric Button Head Socket Cap Screws — Low-Profile Allen Drive for Clean, Snag-Free Assemblies

When a standard socket cap screw sticks up too far, or you need a fastener that looks intentional rather than industrial, metric button head socket cap screws are the go-to choice. Makers, robotics builders, electronics assemblers, and furniture fabricators all reach for this style when clearance is tight or aesthetics matter — and a protruding hex head just won’t do.

Each pack contains 100 pieces of the same size. Available in metric thread sizes M2.5, M3, M4, M5, and M6, with lengths ranging from 4mm (≈5/32") to 60mm (≈2-3/8"). The wide, low-profile dome head distributes clamping load over a larger surface area than a standard cap head, reducing the risk of pull-through in softer materials. Driven by a standard metric hex (Allen) key — no special tools required.

Typical applications include assembling aluminum extrusion frames and 3D printer structures, securing panels on electronics enclosures and control boxes, fastening robotics chassis components where a snag-free surface is critical, and mounting hardware on furniture or cabinetry where a clean, low-profile look is desired.

🔩 Thread Compatibility: ISO metric coarse thread (M2.5×0.45, M3×0.5, M4×0.7, M5×0.8, M6×1.0) — fits standard metric nuts, threaded inserts, and tapped holes. Not compatible with UNC/UNF inch threads.

⚠️ Material Note: Material grade is not specified in the listing title. Contact us to confirm the exact grade before ordering for corrosion-sensitive or load-critical applications.

✅ Key Features of These Metric Button Head Socket Cap Screws

🔘Low-Profile Dome Head Design — The wide, rounded button head sits closer to the surface than a standard socket cap, reducing snag points and giving assemblies a cleaner, more finished appearance without countersinking.
🔧Hex (Allen) Socket Drive — Internal hex socket allows high torque in confined spaces; compatible with standard metric hex keys (typically 1.5mm for M2.5 up to 4mm for M6).
📐Wide Metric Size Range — Covers M2.5 through M6 in lengths from 4mm (≈5/32") to 60mm (≈2-3/8"), making it easy to find the right fit for electronics, robotics, and structural assemblies.
📦100-Piece Pack — Each pack contains 100 screws of the same size — enough for a full project build or restocking your parts bin without over-ordering.
⚙️Broad Load Distribution — The wider head diameter compared to standard socket cap screws spreads clamping force over a larger area, reducing pull-through risk in softer materials like plastic, wood, and thin aluminum sheet.
🧲Compatible with Threaded Inserts — Works seamlessly with heat-set brass inserts in 3D-printed parts and Helicoil inserts in aluminum, making these metric Allen bolts a staple for maker and prototyping workflows.

📐 Technical Specifications — Button Head Socket Cap Screws

Head Style	Button Head (low-profile dome / mushroom)
Drive Type	Internal Hex (Allen / Socket)
Thread Standard	ISO Metric Coarse (DIN 7380)
Available Thread Sizes	M2.5, M3, M4, M5, M6
Available Lengths	4mm (≈5/32") to 60mm (≈2-3/8") — see variant options
Pack Quantity	100 pieces per pack
Material	Contact us to confirm
Finish	See variant options
Hex Key Size	M2.5: 1.5mm / M3: 2mm / M4: 2.5mm / M5: 3mm / M6: 4mm (typically)
Head Angle	Flat underside (no countersink required)
Compatible Standards	DIN 7380, ISO 7380

❓ Frequently Asked Questions

How do I choose the right size and length for my project?

Select the thread diameter (M2.5, M3, M4, M5, or M6) to match your tapped hole or nut. For length, measure the thickness of the material being clamped and add the required thread engagement — typically 1.0–1.5× the screw diameter into the receiving material. For example, an M3 screw fastening a 5mm panel into a 5mm aluminum block would generally need around 10mm total length. The button head sits above the surface, so no countersinking is needed.

What material are these button head screws made from?

Please contact us to confirm the exact material grade before ordering. Button head socket cap screws in this style are generally available in alloy steel (black oxide or zinc-plated) or stainless steel. If material grade is critical for your application, reach out and we’ll confirm the spec.

Are these screws suitable for outdoor or corrosive environments?

Suitability for outdoor use depends on the material grade. Stainless steel variants generally offer good corrosion resistance for outdoor and light marine environments. Alloy steel variants with zinc or black oxide coating are typically intended for indoor or protected applications. Contact us to confirm the material before use in wet or corrosive conditions.

What thread standard do these use — are they compatible with standard metric nuts and inserts?

These screws use standard ISO metric coarse threads (M3×0.5, M4×0.7, M5×0.8, M6×1.0, M2.5×0.45). They are compatible with standard metric nuts, threaded inserts, and tapped holes of the matching size. They are not compatible with UNC/UNF inch-standard threads.

What hex key (Allen wrench) size do I need?

The required hex key size varies by screw diameter. As a general guide for metric button head screws: M2.5 typically uses a 1.5mm hex key, M3 uses 2mm, M4 uses 2.5mm, M5 uses 3mm, and M6 uses 4mm. Always verify with the specific fastener spec sheet before driving to avoid stripping the socket.

Why choose a button head over a standard socket cap head?

Button head screws have a wider, lower-profile dome-shaped head compared to the taller cylindrical head of standard socket cap screws. This makes them ideal when clearance above the surface is limited, or when you want a clean, snag-free finish without countersinking. They are commonly used in electronics enclosures, robotics frames, furniture hardware, and 3D printer assemblies.

Can I use these in aluminum, plastic, or 3D-printed parts?

Yes. These metric button head Allen bolts are widely used in aluminum extrusion assemblies, plastic enclosures, and 3D-printed frames — especially in robotics and maker projects. For plastic or 3D-printed parts, use threaded inserts (e.g., heat-set brass inserts) to improve thread strength and prevent stripping. In aluminum, standard tapped holes or threaded inserts both work well.

🛒 Select your size above, then add to cart — ships from our US warehouse.