M3 M4 Pozi Pan Head Machine Screws A2 Stainless Steel — Multiple Sizes & Pack Quantities

A general rule of thumb is that the screw length should be approximately 2–3 times the diameter for most materials. For example, an M3 screw typically works well at 10–25mm (3/8"–1") for light-duty panel fastening, while longer lengths like 30–50mm (1.2"–2") suit thicker assemblies. Always measure the combined thickness of the materials being joined and add 3–5mm for thread engagement into the receiving material or nut.

A2 stainless steel (304 grade) generally has a tensile strength of approximately 500–700 MPa, depending on the specific manufacturing process. These screws are suitable for general-purpose fastening in light to medium-duty applications. For structural or high-load applications, please contact us to confirm suitability for your specific use case.

A2 stainless steel offers good corrosion resistance and is generally suitable for outdoor use in most environments, including light coastal exposure. For highly aggressive marine or saltwater environments, A4 (316) stainless steel is typically recommended. These screws perform well in garden furniture, outdoor enclosures, and general exterior applications where moderate weather resistance is needed.

These screws use the ISO metric coarse thread standard. M3 has a 3mm nominal diameter with a 0.5mm pitch, and M4 has a 4mm nominal diameter with a 0.7mm pitch. They are compatible with standard metric nuts, threaded inserts, and tapped holes used across electronics, automotive, and general engineering applications worldwide.

Pozi (Pozidriv) screws require a Pozidriv driver bit — not a standard Phillips bit, which can slip and damage the recess. For M3 screws, a PZ1 bit is typically used; for M4 screws, a PZ2 bit is generally appropriate. Using the correct Pozidriv bit prevents cam-out and protects the screw head during installation, especially at higher torque.

These are machine screws designed for use with pre-tapped holes, threaded inserts, or nuts — they are not self-tapping. They work well with metal, hard plastics, and engineered materials where a matching metric thread is already present. For wood or soft materials, a pilot hole combined with a nut or threaded insert is generally required to achieve a secure fastening.

M3 screws (3mm diameter) are typically used for lighter assemblies such as electronics enclosures, small brackets, PCB mounting, and hobby projects. M4 screws (4mm diameter) offer greater load capacity and are commonly used in mechanical assemblies, furniture fittings, and general engineering. Check the thread size of your existing holes or hardware to confirm which size you need before ordering.