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Energizer 4W Dimmable LED ST64 Filament Bulb - Smokey Glass, Cool White, E27, 4000K

£299
The RRP is the manufacturer's recommended retail price of the item.
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Description

The Energizer ST64 is a 4W dimmable LED filament bulb with a smokey grey glass envelope, E27 screw base, and visible LED filament arrangement mimicking traditional incandescent bulb construction. The bulb produces 320 lumens at 4000K cool white, replacing 40W incandescent bulbs while drawing just 4W from the mains. The smokey glass diffuses light evenly while maintaining the decorative filament visibility that defines the ST64 squirrel-cage aesthetic.

Designed for pendant fittings, exposed-bulb chandeliers, industrial-style fixtures and table lamps where the bulb itself forms part of the visual design, the ST64 pairs functional light with decorative presence. The 4000K colour temperature provides neutral-to-cool white light that suits kitchens, utility rooms, garages and workshops where colour accuracy and clarity matter more than warmth. Dimming compatibility allows brightness adjustment from full output down to around 10%, controlled by a standard LED-compatible dimmer switch.

The smokey grey glass finish reduces glare when the bulb is viewed directly and softens the intensity of the LED filament, making the bulb more comfortable to look at in exposed-socket fittings. The ST64 shape measures 64mm in diameter and 145mm in total length including the E27 base, so it sits well in medium-to-large pendant shades and multi-bulb chandeliers without appearing undersized. The 15-year rated lifespan (based on 3 hours daily use) means the bulb should outlast most fittings it's installed in.

Specification
Weight (KG) 0.05
Width (mm) 64
Height (mm) 145
Depth (mm) 64
Wattage 4.5W
Lumen 320
Lamp Shape ST64
Lamp Base E27
Energy Rating G
Kelvin 4,000K
Colour Temperature Cool White
Dimmable Yes
Beam Angle 320
LED or Halogen LED
Frequently Asked

Is this bulb dimmable?

Yes. The Energizer ST64 is compatible with most LED-rated dimmer switches and can be dimmed from full brightness down to approximately 10%. Performance varies between dimmer models, so pairing with a quality LED-compatible dimmer is recommended.

What does 4000K cool white look like?

4000K sits in the neutral-to-cool white range. It appears noticeably whiter and crisper than warm white (2700K-3000K) bulbs, without the clinical blue tone of daylight bulbs (5000K+). This temperature suits task-focused spaces like kitchens, workshops and offices.

What wattage incandescent does this replace?

The bulb produces 320 lumens at 4W, replacing a traditional 40W incandescent bulb. The packaging states 40W replacement despite the higher-wattage claim in some listings.

Will the smokey glass reduce light output?

Yes, slightly. The smokey grey tint diffuses and softens the light, reducing perceived brightness compared to a clear ST64 bulb of the same lumen rating. The trade-off is reduced glare and a more visually comfortable bulb in exposed fittings.

Shipping & Returns

Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

To arrange a return, call us on 020 8149 5199 or use our contact page.

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Every product arrives brand new with the full manufacturer warranty. Found it cheaper elsewhere? Ask us about a price match.

Light source

Takes standard bulbs

Takes standard E27 bulbs, so you choose the brightness and colour to suit the room.

Ordering with us

Free delivery over £99

Free delivery on orders over £99, in the UK and worldwide. Easy returns within 14 days, subject to our returns policy. Full manufacturer warranty included.

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    Description

    The Energizer ST64 is a 4W dimmable LED filament bulb with a smokey grey glass envelope, E27 screw base, and visible LED filament arrangement mimicking traditional incandescent bulb construction. The bulb produces 320 lumens at 4000K cool white, replacing 40W incandescent bulbs while drawing just 4W from the mains. The smokey glass diffuses light evenly while maintaining the decorative filament visibility that defines the ST64 squirrel-cage aesthetic.

    Designed for pendant fittings, exposed-bulb chandeliers, industrial-style fixtures and table lamps where the bulb itself forms part of the visual design, the ST64 pairs functional light with decorative presence. The 4000K colour temperature provides neutral-to-cool white light that suits kitchens, utility rooms, garages and workshops where colour accuracy and clarity matter more than warmth. Dimming compatibility allows brightness adjustment from full output down to around 10%, controlled by a standard LED-compatible dimmer switch.

    The smokey grey glass finish reduces glare when the bulb is viewed directly and softens the intensity of the LED filament, making the bulb more comfortable to look at in exposed-socket fittings. The ST64 shape measures 64mm in diameter and 145mm in total length including the E27 base, so it sits well in medium-to-large pendant shades and multi-bulb chandeliers without appearing undersized. The 15-year rated lifespan (based on 3 hours daily use) means the bulb should outlast most fittings it's installed in.

    Specification
    Weight (KG) 0.05
    Width (mm) 64
    Height (mm) 145
    Depth (mm) 64
    Wattage 4.5W
    Lumen 320
    Lamp Shape ST64
    Lamp Base E27
    Energy Rating G
    Kelvin 4,000K
    Colour Temperature Cool White
    Dimmable Yes
    Beam Angle 320
    LED or Halogen LED
    Frequently Asked

    Is this bulb dimmable?

    Yes. The Energizer ST64 is compatible with most LED-rated dimmer switches and can be dimmed from full brightness down to approximately 10%. Performance varies between dimmer models, so pairing with a quality LED-compatible dimmer is recommended.

    What does 4000K cool white look like?

    4000K sits in the neutral-to-cool white range. It appears noticeably whiter and crisper than warm white (2700K-3000K) bulbs, without the clinical blue tone of daylight bulbs (5000K+). This temperature suits task-focused spaces like kitchens, workshops and offices.

    What wattage incandescent does this replace?

    The bulb produces 320 lumens at 4W, replacing a traditional 40W incandescent bulb. The packaging states 40W replacement despite the higher-wattage claim in some listings.

    Will the smokey glass reduce light output?

    Yes, slightly. The smokey grey tint diffuses and softens the light, reducing perceived brightness compared to a clear ST64 bulb of the same lumen rating. The trade-off is reduced glare and a more visually comfortable bulb in exposed fittings.

    Shipping & Returns

    Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

    Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

    To arrange a return, call us on 020 8149 5199 or use our contact page.