Fastshifter Bulb Self-Tapping Screw SS410 4.2×34mm – 1 pcs

The Fastshifter Bulb self-tapping screw 4.2 × 34 mm is used to fix decking clips and hidden fasteners into aluminium joists. It is self-drilling, so no pre-drilling is required in the joist profile, and its low-profile bulb head sits flush inside the clip.

Material: SS410 stainless, black, driven with a T15 bit. Supplied as 1 pcs.

Key features

• 4.2 × 34 mm — sized for standard clip and joist combinations.
• Self-drilling point — no pre-drilling in aluminium joists.
• Bulb head seats neatly in the fastener, keeping boards flat.
• SS410 stainless, black for corrosion resistance and a discreet finish.
• T15 drive for good torque transfer and low cam-out.
• Suitable for exterior use in wet and exposed conditions.

Where it is used

• Fixing hidden decking clips into aluminium joists.
• WPC and composite decking on metal substructures.
• Soft, dimensionally stable timber boards such as thermally modified pine.
• Terrace, balcony and roof deck installations.

SS410 is a harder stainless grade than the usual A2 or A4, which is what lets it drill aluminium cleanly. In ordinary steel joists pre-drilling is still recommended, and SS410 is not the right choice for larch or dense hardwoods.