4W Dimmable LED ST64 Spiral Filament Bulb - Amber 1800K E27

The Knightsbridge ST64 is a 4W dimmable LED bulb with a visible spiral filament behind amber-tinted glass, producing 225 lumens of 1800K extra-warm white light. The E27 Edison screw base fits standard UK lamp holders and the ST64 squirrel-cage shape measures 64mm diameter by 140mm height, making it compatible with exposed pendants, table lamps and wall lights where the bulb itself forms part of the visual design.

Designed as a direct replacement for 40W incandescent bulbs in decorative fittings, the ST64 combines the warm amber glow and visible filament aesthetic of vintage Edison bulbs with LED efficiency and a longer lifespan. The 1800K colour temperature sits well below the standard 2700K warm white, producing a candle-like orange-amber light that works in period interiors, hospitality settings and residential rooms where atmosphere matters more than task lighting. The spiral filament remains visible when the bulb is off, so the bulb looks intentional even when not lit.

The bulb is dimmable with most trailing-edge dimmers, allowing light levels to be adjusted from full 225-lumen output down to a low glow without flicker. Dimmer compatibility varies by manufacturer and model, so testing before full installation is recommended. The amber glass tint deepens the warm tone of the 1800K output, creating a noticeably golden cast when viewed against white walls or ceilings. The 2-year warranty covers LED driver failure and premature filament burnout under normal operating conditions.

Product Specification Sheet

Is this bulb dimmable?

Yes. The bulb is compatible with most trailing-edge dimmers and can be adjusted from full 225-lumen output down to a low glow. Dimmer compatibility varies by manufacturer, so testing with your specific dimmer before installation across multiple fittings is recommended.

What colour temperature is 1800K?

1800K is extra-warm white, producing a candle-like orange-amber glow noticeably warmer than standard 2700K warm white bulbs. The amber glass tint deepens this effect, creating a golden cast similar to vintage incandescent filament bulbs.

What does this bulb replace?

The 4W LED output of 225 lumens is equivalent to a 40W incandescent bulb. It suits decorative fittings where ambient light or mood lighting is the priority rather than task lighting or high-output illumination.

Can this bulb be used in enclosed fittings?

The IP20 rating means the bulb is suitable for dry indoor locations only. LED filament bulbs generate less heat than incandescent equivalents, but some enclosed fittings may still trap heat and reduce lifespan. Check the fitting manufacturer's guidance on maximum wattage and heat dissipation before use in fully enclosed shades.