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A wider head means a stronger grip in thin material — that’s exactly what these Phillips truss head self‑tapping screws deliver. Made from genuine A2 / 304 stainless steel, they resist rust in humidity, rain, and mild chemicals without any coating that can wear off. The oversized truss head spreads clamping force across a larger area than a standard pan head, preventing pull‑through in sheet metal, plastic, and soft wood. Sharp, fully‑formed threads cut their own path as you drive, so there’s no need for a pre‑tap or pilot hole in most thin‑gauge materials. This series covers the four most‑requested small metric sizes: M3, M3.5, M4, and M4.2, giving you the exact fastener for electronics enclosures, automotive trim, brackets, and general‑shop repairs.
| Thread Spec. | Thread Diameter (d) | Head Diameter (dk) | Head Thickness (k) | Typical Lengths (mm)* | Head Style | Drive | Material |
|---|---|---|---|---|---|---|---|
| M3 | 3.0 mm | 6.5 mm | 1.6 mm | 6 – 30 | Truss Head | Phillips | A2 304 Stainless Steel |
| M3.5 | 3.5 mm | —** | —** | 8 – 35 | Truss Head | Phillips | A2 304 Stainless Steel |
| M4 | 4.0 mm | 8.7 mm | 2.1 mm | 8 – 40 | Truss Head | Phillips | A2 304 Stainless Steel |
| M4.2 | 4.2 mm | 8.8 mm | 2.2 mm | 10 – 50 | Truss Head | Phillips | A2 304 Stainless Steel |
* Length is thread length only (measured from under the head). Head dimensions for M3.5 are not in the standard chart — please refer to product photos or contact us for the exact values. All screws are fully threaded.
A truss head has a larger, flatter bearing surface that spreads the clamping force wider. This stops the screw from pulling through thin sheet metal, plastic, or soft wood — often eliminating the need for a separate washer.
In thin sheet metal up to about 1.5 mm, you can usually self‑tap directly. For thicker steel or hard materials, a pilot hole about 80% of the thread diameter will reduce driving torque and ensure the cleanest thread engagement.
A2 / 304 stainless is highly resistant to red rust and is suitable for outdoor, marine‑above‑waterline, and humid environments. It won’t corrode like carbon steel. For constant saltwater submersion, 316 would be a better choice.
No. All lengths are the thread length only, measured from directly under the head to the tip. This makes it easy to match the screw to your material thickness.
