ST4.2 self-tapping screws

sheet-metal (ISO 1478)

5 documented uses, taken from manufacturer catalogs, service manuals and teardowns.

Pilot hole

3.6-3.8 mm in 1.0-2.0 mm steel

Too tight and the head snaps or the boss splits; too loose and the thread strips on the first removal.

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Most common size for automotive plastic trim; often uses an integrated washer (flange).
Most TV, appliance, HVAC and power-tool service documents list only a driver type or a part number, never a thread size - so a screw kit sold as 'fits brand X' is usually a seller's guess, not an OEM spec. Measure the old screw before buying.