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Security and corrosion resistance come together in these A2 / 304 stainless steel countersunk Torx anti‑theft self‑tapping screws. The 90° flat head sits flush for a clean, snag‑free finish, while the 6‑lobe Torx recess with a central security pin prevents unauthorized removal when you use the correct Torx Security bit — ideal for public fixtures, electronic access panels, outdoor signs, and high‑value equipment enclosures. Made from genuine 304 stainless, they won't red‑rust in rain, humidity, or mild chemical environments, and there's no surface coating to chip or wear off. The sharp, self‑tapping coarse thread cuts its own path into sheet metal, plastic, wood, and composites — no pilot hole needed in most thin materials. Available in four exact diameters — M2.9, M3.5, M3.9, and M4.8 — with matched Torx bit sizes (T10, T15, T20, T25) and a range of lengths, this series gives you a secure, professional fastening solution for applications where tamper resistance is required.
| Size | Thread Diameter (D) | Head Diameter (M) | Thread Pitch (P) | Head Thickness (K) | Torx Size (B) | Available Lengths (mm)* | Head Style | Material & Finish |
|---|---|---|---|---|---|---|---|---|
| M2.9 | 2.9 mm | 5.2 – 5.5 mm | 1.06 mm | 1.8 mm | T10 | 6 – 25 | Countersunk Flat 90° | A2 304 Stainless, Plain |
| M3.5 | 3.5 mm | 3.9 mm | 1.26 mm | 2.3 mm | T15 | 8 – 30 | Countersunk Flat 90° | A2 304 Stainless, Plain |
| M3.9 | 3.9 mm | 7.14 – 7.5 mm | 1.34 mm | 2.7 mm | T20 | 10 – 40 | Countersunk Flat 90° | A2 304 Stainless, Plain |
| M4.8 | 4.8 mm | 8.9 – 9.3 mm | 1.59 mm | 3.2 mm | T25 | 12 – 50 | Countersunk Flat 90° | A2 304 Stainless, Plain |
* Lengths are overall length (including head). Torx Security bits (T10, T15, T20, T25) are required for installation and removal. All dimensions show tolerance ranges per the manufacturer’s drawing.
You’ll need a Torx Security bit (also called a Tamper‑Proof Torx bit). Standard Torx bits will not work because the security pin in the center of the recess requires a hollow‑point bit. The matching sizes are T10 (M2.9), T15 (M3.5), T20 (M3.9), and T25 (M4.8).
In thin sheet metal (up to about 1.2 mm), soft plastics, and wood, you can drive them directly without a pilot hole. For thicker steel or hard materials, a pilot hole about 80% of the thread diameter is recommended to reduce driving torque and ensure clean thread engagement.
Yes. 304 stainless is the standard for outdoor and marine‑above‑waterline fasteners. It resists red rust effectively. For permanent saltwater submersion, 316 would be even better, but for outdoor enclosures, signage, and coastal installations, 304 provides excellent long‑term protection.
All listed lengths are overall length, measured from the top of the countersunk flat head to the tip. This makes it easy to match the screw to your total material thickness.
