303 Stainless Steel Knurled Thumb Screws M3 — Thin Head, Multiple Lengths

Measure the total thickness of the material you need to clamp or fasten, then add 2–3mm for thread engagement. For example, if your panel is 3mm thick, an M3*6mm (≈1/4") screw is typically sufficient. If you're fastening through two stacked 3mm panels, an M3*8mm (≈5/16") or M3*10mm (≈3/8") would generally be more appropriate. Available lengths in this listing range from 5mm (≈3/16") to 20mm (≈25/32").

These screws are designed for hand-tightened, low-torque applications such as panel fastening, enclosure assembly, and light-duty clamping. 303 stainless steel generally provides adequate tensile strength for these use cases. For high-load or vibration-critical structural applications, a tool-driven fastener with a higher torque spec is typically recommended.

303 stainless steel offers good corrosion resistance for most indoor and light outdoor use, including humid environments and mild moisture exposure. It is generally not recommended for direct saltwater immersion or heavily corrosive chemical environments — in those cases, 316 stainless steel is typically the better choice.

These screws use the M3 metric coarse thread standard (ISO metric). They are compatible with standard M3 threaded holes, M3 brass heat-set inserts, and M3 hex nuts. They are not compatible with imperial #4-40 UNC threads or other non-metric standards without an adapter.

Yes — these are a popular choice for exactly those applications. The M3 size is a standard fastener in electronics enclosures, RC car and drone frames, 3D printer axis mounts, and laboratory instrument panels. The thin knurled head allows tool-free access in tight spaces, and the stainless steel construction holds up to repeated removal and reinstallation.

You select the quantity when you choose your variant: 1, 3, 5, 8, or 10 pieces. All pieces in a single order are the same M3 thread diameter and the length you select. If you need multiple lengths, simply add each as a separate item to your cart.

The knurled grip pattern is machined directly into the stainless steel head — it is not a coating or surface treatment. Under normal hand-tightening use, the texture generally maintains its grip effectiveness over many installation and removal cycles. Avoid using pliers or tools on the knurled head, as this can deform the pattern over time.