M3–M5 A2 Stainless Steel Phillips Countersunk Machine Screws — 3mm to 200mm
A2 stainless steel Phillips countersunk machine screws covering four metric thread sizes — M3, M3.5, M4, and M5 — with an exceptionally wide length range from 3mm to 200mm. Whether you need short screws for electronics and precision assemblies or long screws for structural and fabrication work, this listing covers the full spectrum in a single product.
The countersunk (flat) head profile is designed to sit flush with or below the surface of the workpiece when driven into a properly prepared countersunk hole, delivering a clean, professional finish. A2 stainless steel (304-grade) provides inherent corrosion resistance that carbon steel and zinc-plated fasteners cannot match over time, making these screws suitable for indoor, outdoor, and mildly corrosive environments.
Available in pack sizes of 1, 5, 10, and 50 pieces — from single-piece orders for prototyping or repair to 50-piece packs for production and workshop stock.
🔩 Compatibility: ISO metric thread standard — compatible with standard M3, M3.5, M4, and M5 metric nuts, threaded inserts, and tapped holes. Always verify thread pitch and hole diameter before ordering.
✅ Key Features of These A2 Stainless Steel Phillips Countersunk Machine Screws
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🔩A2 Stainless Steel (304-Grade) — Inherent corrosion resistance suitable for indoor, outdoor, and mildly corrosive environments. Significantly more durable than carbon steel or zinc-plated alternatives over time.
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📐Countersunk (Flat) Head — 90° — Conical underside seats flush with or below the workpiece surface when driven into a properly countersunk hole. Ideal for applications requiring a clean, flush finish.
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🔧Phillips Drive — Standard cross-head drive compatible with PH1 (M3–M3.5) and PH2 (M4–M5) Phillips screwdrivers and power tools.
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📏4 Thread Sizes, 3mm to 200mm — M3, M3.5, M4, and M5 across an exceptionally wide length range to cover precision electronics, general fabrication, and structural applications.
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📦Flexible Pack Sizes — Available in 1, 5, 10, and 50-piece packs to suit single-project needs, prototyping, workshop stock, or production quantities.
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⚙️ISO Metric Thread — Compatible with standard metric nuts, threaded inserts, and tapped holes for reliable engagement across M3–M5 sizes.
📐 Technical Specifications — A2 Stainless Steel Phillips Countersunk Machine Screws
| Thread Standard |
ISO Metric |
| Drive Type |
Phillips (PH / Cross Head) |
| Head Style |
Countersunk (Flat Head, 90°) |
| Material |
A2 Stainless Steel (304-Grade) |
| Thread Diameters |
M3, M3.5, M4, M5 |
| Length Range |
3mm to 200mm (see variant selector for available lengths per size) |
| Pack Sizes |
1, 5, 10, 50 Pcs |
| Recommended Driver |
PH1 (M3–M3.5) / PH2 (M4–M5) Phillips Screwdriver |
| Head Angle |
90° Countersunk |
| Finish |
Natural Stainless (A2 / 304) |
| Country of Origin |
Contact us to confirm |
⚠️ Note: Countersunk screws require a properly prepared countersunk hole for the head to sit flush. Stainless steel fasteners can be susceptible to galling (thread seizure) — apply anti-seize lubricant when threading into stainless steel nuts or tapped holes. Always use the correct Phillips driver size to avoid cam-out and head damage. Screw length is measured from the top of the head to the tip.
❓ Frequently Asked Questions
What does A2 stainless steel mean?
A2 stainless steel is the ISO designation for 304-grade austenitic stainless steel. It offers good general corrosion resistance suitable for indoor, outdoor, and mildly corrosive environments. For marine or high-chloride environments, A4 (316-grade) stainless steel is recommended.
What is the difference between Phillips and Pozi drive?
Phillips (PH) and Pozi (PZ) are both cross-head drive types but are not interchangeable. Phillips has a simple cross recess, while Pozi has additional diagonal recesses providing better driver engagement and reduced cam-out. These screws feature a Phillips drive. Always use the correct driver type and size.
What screwdriver size do I need?
M3–M3.5 typically require a PH1 Phillips driver. M4–M5 typically require a PH2 Phillips driver. Using the correct size is important to avoid cam-out and head damage.
Do I need to pre-drill a countersunk hole?
Yes. For the screw head to sit flush with the surface, you need to drill a clearance hole for the shank and countersink the top of the hole to match the screw head angle (typically 90°). Driving a countersunk screw into an unprepared hole will leave the head proud of the surface.
Can stainless steel screws gall or seize during installation?
Yes. Stainless steel fasteners are susceptible to galling when threading into stainless steel nuts or tapped holes. Apply anti-seize lubricant to the threads before installation, drive at a slow and steady speed, and avoid over-tightening.
How do I choose the right screw length?
For machine screws used with a nut, the screw should extend at least 1–2 thread pitches beyond the nut when fully tightened. For screws threading into a tapped hole, aim for at least 1.5× the thread diameter of engagement. For countersunk screws, length is measured from the top of the head (flush with the surface) to the tip.
Are these screws suitable for outdoor use?
Yes. A2 stainless steel provides significantly better corrosion resistance than carbon steel or zinc-plated fasteners and is suitable for outdoor and humid environments. For marine or coastal applications with high chloride exposure, A4 (316) stainless steel is recommended.
🛒 Select your size and pack quantity above, then add to cart — ships from our US warehouse.
