Knurled Thumb Screws Flat Head Hand Grip Knob 303 Stainless Steel M3 M4 M5 M6

Match the thread diameter (M3, M4, M5, or M6) to your existing threaded hole or insert. For length, measure the panel thickness plus any standoff depth — the screw shank should engage at least 1× the thread diameter into the mating material for reliable hold. For thin sheet metal panels (typically 1–2 mm), shorter lengths like 6–10 mm are usually sufficient.

These thumb screws are designed for tool-free, hand-tightened applications such as access panels and inspection covers — not for structural or high-torque joints. For load-bearing connections, a hex or socket head cap screw tightened with a tool is more appropriate.

303 stainless steel provides good corrosion resistance in dry indoor environments. It is not recommended for continuous exposure to saltwater, chlorinated water, or highly acidic environments. For outdoor or marine use, 316 stainless steel would be a better choice.

Yes — M3, M4, M5, and M6 are standard ISO metric thread sizes and will mate with any conforming metric nut, threaded insert, or tapped hole of the same diameter and pitch. Always confirm the thread pitch of your insert matches the screw before ordering.

Most ATX and mid-tower cases use 4–8 thumb screws per side panel. A 10-piece pack covers a typical dual-panel build with spares. If you are outfitting multiple cases or a rack of enclosures, the 50- or 100-piece packs offer a lower per-unit cost.

Yes. These thumb screws work well with T-slot aluminum extrusion frames when used with the appropriate T-nut or threaded insert. Select the thread diameter that matches your extrusion's T-nut specification — M3 and M4 are most common for 20-series profiles, while M5 and M6 suit 30- and 40-series profiles.

M4 screws have a larger thread cross-section and typically a wider knurled head, providing more surface area for finger grip and higher clamping force at the same hand torque. M3 is better suited for lightweight panels and compact electronics where space is limited. For general panel-fastening where either size fits, M4 is the more versatile choice.