M3 M4 M5 M6 Knurled Thumb Screws Stainless Steel Hand Grip Knob Bolt φ9/13/16mm

Measure the total stack-up thickness your screw must pass through — panel material plus any washers or spacers — and add at least 3–5 thread pitches of engagement depth in the receiving nut or threaded insert. For example, a 2 mm aluminum panel with a 3 mm threaded insert needs roughly 5–6 mm of shank; choose the next available length up (e.g., M4×8 or M4×10) to ensure full thread engagement without bottoming out.

Straight Steps heads have a flat top surface and a cylindrical body — ideal when you want a flush, industrial look or need to stack multiple fasteners in a row without height variation. Arc Steps heads have a gently domed crown that makes them easier to locate by touch in confined spaces and gives a slightly lower visual profile when viewed from the side. Both share the same knurl pattern and thread specifications for a given size.

These thumb screws are designed for hand-tightened, tool-free applications such as panel retention, enclosure lids, and access covers — not for high-torque structural joints. 304 stainless steel provides adequate tensile strength for typical panel-fastening loads, but if your application requires torque beyond what can be applied by hand, a hex-socket or Phillips drive fastener is more appropriate. For vibration-prone environments, consider adding a nylon-insert nut or thread-locking compound on the receiving side.

304 stainless steel offers good resistance to oxidation and mild corrosion in most indoor and light outdoor environments. It can show surface staining if exposed to prolonged contact with chlorides (e.g., salt spray or pool environments) or if scratched and left in a highly humid setting. For marine or heavily corrosive environments, 316 stainless steel would be a better choice. For typical PC builds, workshop enclosures, and indoor DIY projects, 304 performs reliably without special maintenance.

Yes. The threads follow the ISO metric coarse standard, so they are compatible with any standard M3, M4, M5, or M6 hex nut, nylon-insert locknut, T-nut, or heat-set threaded insert of the matching diameter. Always verify that the pitch of your receiving hardware matches the coarse-thread pitch for the chosen diameter (e.g., M4 coarse = 0.7 mm pitch).

The head diameter affects both the bearing surface area and the visual footprint. φ9 mm heads are compact and suit dense layouts such as PCB standoffs or small enclosure panels where clearance between fasteners is limited. φ13 mm heads offer a larger grip surface and spread clamping load over a wider area — good for medium-thickness panels. φ16 mm heads provide the most grip and the largest bearing surface, making them the best choice for thicker panels, softer materials like acrylic or wood, or applications where you want maximum hand-torque leverage. Note that head diameter is encoded in the Size option (e.g., D9, D13, D16).

The notation follows the pattern: Thread Diameter × Shank Length – Head Diameter × Head Height. So M4*12-D13*9 means: M4 thread, 12 mm shank length, 13 mm head diameter, 9 mm head height. Use the shank length (L) to match your panel stack-up, and the head diameter (D) to choose the grip size that fits your layout.