M3.5-M4 Aluminum Alloy Knurled Thumb Screws Hand Grip Knob Bolts 4.5mm-30mm

Match the thread diameter (M3.5 or M4) to your tapped hole or threaded insert, then select a shaft length that provides at least 1.5× the thread diameter in engagement depth — for M4, that means at least 6 mm of thread engagement. For thin panels (1–3 mm), shorter lengths like 4.5–6 mm work well; for thicker brackets or through-bolt applications, 16–30 mm lengths are appropriate.

No. M3.5 (3.5 mm nominal diameter, 0.6 mm pitch) and M4 (4.0 mm nominal diameter, 0.7 mm pitch) are distinct thread standards and are not interchangeable. Using the wrong size will strip the threads in your component. Always verify the thread diameter of your existing hole or insert before ordering.

Aluminum alloy thumb screws are suitable for light-duty panel retention, access covers, and non-structural brackets where hand-tightening torque is sufficient. They are not recommended for high-vibration environments or structural joints that require torque-wrench tightening. For applications requiring higher clamping force, consider steel knurled screws instead.

Anodizing is an electrochemical process that integrates the color into the aluminum oxide layer rather than sitting on top as paint. This makes it significantly more resistant to chipping and peeling than painted finishes. Color may gradually fade with prolonged UV exposure or abrasive contact, but for typical indoor use — repeated hand-tightening on enclosures or equipment — the finish holds well over time.

The anodized aluminum construction offers moderate corrosion resistance suitable for dry indoor environments. For outdoor use, high-humidity settings, or exposure to salt air, the anodized layer provides limited protection compared to stainless steel. If your application involves outdoor exposure, consider stainless steel thumb screws or apply a compatible sealant over the threads.

The Qty(pcs) option lets you choose between a single screw (useful for replacements or sampling a color/size) and a 10-piece pack (cost-effective for full panel builds or stocking a workshop). The per-unit price is lower in the 10-piece pack. Both options ship the same size and color as selected in the Sizes and Colour dropdowns.

Many camera cage accessories use M4 threads for accessory mounting points. The M4 variants in this listing (M4×25 mm and M4×30 mm) are compatible with M4-threaded holes found on common cage components. Always verify the thread specification of your specific cage or accessory before purchasing, as some manufacturers use non-standard thread sizes.