🔩 Product Overview: M2–M4 Flat Round Head Hex Socket Screws – A2 Stainless Steel (Grade 4.8)
Need a low‑profile fastener with a smooth, snag‑free head and the torque power of a hex drive? These M2, M3, and M4 flat round head hex socket screws (sometimes called button head Allen screws) are made from A2 (304) stainless steel – so they resist rust and corrosion indoors and out. The rounded, low‑profile head sits flush on surfaces, while the internal hex socket lets you apply high torque without stripping or cam‑out. Fully threaded with standard coarse metric pitch, they're perfect for furniture assembly, electronics enclosures, machinery guards, and marine hardware. Lengths from 3mm to 50mm (measured under the head), Grade 4.8 strength – reliable for everyday DIY and professional use.
✨ Why These A2 Stainless Hex Socket Screws Are a Workshop Essential
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A2 (304) stainless steel – Excellent corrosion, oxidation, and heat resistance. High strength and toughness. Ideal for outdoor furniture, kitchen gear, and industrial applications.
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Flat round (button) head – Low‑profile domed head with a smooth surface. Won't snag on cables or fabric – looks clean on panels and visible assemblies.
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Hex socket (Allen) drive – Internal hex provides positive engagement, eliminates cam‑out, and allows high torque without stripping. Use a standard metric hex key.
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Metric sizes M2, M3, M4 – The most common small diameters for electronics, appliances, furniture, and light machinery.
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Lengths from 3mm to 50mm (under head) – Short screws for thin panels, longer ones for through‑hole applications. Choose exactly what you need.
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Fully threaded, coarse metric pitch – M2x0.4, M3x0.5, M4x0.7. Threads run the entire shank length for maximum grip and easy nut engagement.
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Grade 4.8 strength – Reliable for general fastening in furniture, machinery, and structural assemblies.
📏 Technical Specifications – M2–M4 Flat Round Head Hex Socket Screws (A2 Stainless)
| Specification |
M2 |
M3 |
M4 |
| Thread Diameter (D) |
2mm |
3mm |
4mm |
| Thread Pitch (P) |
0.4mm |
0.5mm |
0.7mm |
| Head Diameter (DK) – approx |
3.8mm |
7.0mm |
8.6mm |
| Head Thickness (K) – approx |
1.3mm |
1.8mm |
2.0mm |
| Hex Socket Size (S) – approx |
1.5mm |
2.0mm |
2.5mm |
| Material |
304 Stainless Steel (A2 grade) |
| Grade |
4.8 |
| Thread Type |
Fully threaded, coarse |
| Length Range (under head) |
3mm – 50mm (select from options) |
| Drive Style |
Hex key (Allen), metric |
❓ FAQs – M2–M4 Flat Round Head Hex Socket Screws
🔸 Are these screws fully threaded? How is length measured?
Yes – they are fully threaded from just under the head to the tip. Length is measured from the underside of the head (the flat bearing surface) to the tip, not including the head thickness. For example, an M4 x 12mm screw has 12mm of threaded shank below the head.
🔸 What hex key (Allen wrench) size do I need for M2, M3, and M4?
Typically: M2 uses 1.5mm hex key, M3 uses 2.0mm, M4 uses 2.5mm. A standard metric hex key set (1.5mm, 2mm, 2.5mm) will cover all three sizes.
🔸 Will 304 stainless steel rust in outdoor or coastal environments?
304 stainless is highly resistant to moisture, rain, and humidity – perfect for most outdoor use. For direct saltwater immersion or heavy coastal spray, 316 stainless (A4) is better, but for garden furniture, railings, and general outdoor DIY, 304 lasts for years without rust.
🔸 Can I use these screws with nuts, or are they self‑tapping?
These are machine screws – they require a matching metric nut (M2, M3, or M4) or a pre‑tapped hole. They are not self‑tapping. For best corrosion resistance, pair them with 304 stainless nuts.
🔸 What lengths are available for M2, M3, and M4?
We offer lengths from 3mm up to 50mm. Please select your desired length from the dropdown options on the product page. Typical increments: 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50mm (availability varies by diameter).
🔸 Are these screws magnetic?
304 stainless is generally non‑magnetic in its annealed state, but cold forming (like thread rolling) can make it slightly magnetic. A light magnetic response is normal and does not affect corrosion resistance or strength.
