UNC 3/8" & 1/4" Wing Thumb Screws – Single & Double Wing T-Type, Aluminum & Stainless Steel

Match the thread diameter to your existing threaded hole or insert. The 3/8" (≈9.5mm) diameter is generally used for heavier-duty fixtures, enclosures, and structural panels. The 1/4" (≈6.35mm) diameter is more common in lighter assemblies, electronics enclosures, and DIY projects. Always verify the thread specification of your mating part before ordering.

Single wing thumb screws have one protruding tab on one side of the head, allowing tightening with a single finger or thumb in confined spaces. Double wing (T-type) screws have two symmetrical wings, providing more balanced torque and a more secure grip — useful when higher hand-tightening force is needed or when the fastener is accessed frequently.

Select a length that provides adequate thread engagement for your panel or bracket thickness. As a general rule, thread engagement should be at least 1× the thread diameter for aluminum mating parts, and at least 0.5× for steel. Available lengths are 10mm (≈3/8"), 14mm (≈9/16"), 17mm (≈11/16"), and 20mm (≈25/32"). Measure your clearance depth and add the required engagement length.

The aluminum variants are lighter and typically anodized for corrosion resistance under normal indoor conditions. The stainless steel variants offer greater strength, higher corrosion resistance, and are generally better suited for environments with moisture exposure or where higher clamping loads are required. Both share the same thread specifications and head geometry.

The stainless steel variants are generally more suitable for outdoor or high-humidity environments due to their inherent corrosion resistance. The aluminum variants with anodized finish offer reasonable protection for indoor use but may degrade over time in prolonged outdoor exposure. For outdoor applications, we recommend the stainless steel option and suggest confirming suitability with us before ordering.

These thumb screws use UNC (Unified National Coarse) thread standard — 3/8" and 1/4" diameters. They are not metric. If your application uses metric threads (e.g., M6, M8, M10), these screws will not be compatible. Please verify your thread standard before ordering.

As hand-tightened fasteners, wing thumb screws are designed for light to moderate clamping loads — typically sufficient for access panels, enclosure covers, and non-structural assemblies. The double wing (T-type) head generally allows more hand torque than single wing. For precise load specifications, contact us to confirm based on your application.