KIWI design K4 Duo AIO Audio Head Strap with Battery

You've just invested in a Meta Quest 3 or 3S. The headset is impressive — but after 90 minutes, reality catches up with the immersion: the original strap pulls forward, your face bears all the weight, the battery dies and the built-in speakers simply aren't up to what you see on screen.

The K4 Duo exists to solve exactly these four problems. In one piece.

Sessions that don't stop at the worst moment

The Quest 3's native battery lasts about 2 hours under intensive use. It's often right when you're most in the game, in the middle of a client demo, or halfway through a film, that it gives up.

The K4 Duo integrates a 20.4 Wh battery that extends your runtime by 2 to 2.5 extra hours. And thanks to the DualFast 45W system powered by dual PD chips, a single USB-C cable charges both the headset and the strap simultaneously. Full charge time: under 2h30. You plug in, wait half a film, and you're good for half a day.

No more neck pain, no more facial pressure

The Quest 3 is unbalanced by design: all the electronics are at the front, and the standard strap doesn't compensate. Result: the weight pulls forward, the foam compresses your face, and after an hour you're thinking as much about your discomfort as the experience itself.

The K4 Duo places the battery at the back of the head, acting as a natural counterweight. The headset's centre of gravity moves closer to the centre of your skull — zero facial pressure, head upright, neck relaxed. Even after two hours of intensive play. The memory foam on the headband adapts to your head shape and stays where you put it.

Sound that genuinely changes the experience

The Quest's built-in speakers are fine for a quick demo. For true immersion — cinema, narrative gaming, simulation — they fall short. The sound bleeds into the room, everyone hears it, and you lose the sensation of being inside the virtual environment.

The K4 Duo integrates two 40mm dynamic drivers positioned directly over your ears, adjustable on 3 degrees of freedom to fit any head shape. The difference is immediate: the bass is there, the audio details come through, you're inside it. A physical button lets you switch in one second between the K4 Duo earphones and the native speakers — handy in demos to share audio with your audience without removing the headset.

And for the Quest 3S, which has no 3.5mm jack: the K4 Duo runs entirely through USB-C. No adapter, no compromise.

One cable to manage everything

Some solutions need one cable for charging, another for audio, sometimes an adapter in between. That's exactly the kind of friction that breaks immersion before you even put the headset on.

With the K4 Duo, a single USB-C cable handles both power and audio. You plug in, you wear it, you play. Nothing else.

Who is it for?

The K4 Duo is designed for those who use their Quest seriously: long gaming sessions, VR training, professional demonstrations, immersive experiences. If you wear the headset for more than an hour at a time, show VR to clients or learners, or simply want to stop juggling cables and accessories — this is the upgrade that brings it all together.

Technical specifications

• Compatibility: Meta Quest 3 / Quest 3S
• Weight: 459 g
• Dimensions: 250 × 280 × 135 mm
• Battery capacity: 20.4 Wh
• Max charging power: 45W (45W adapter recommended)
• Full charge time: ~2.5 h (headset + strap simultaneously)
• Added battery life: +2 to 2.5 h depending on usage
• Speakers: 2 × 40mm dynamic, adjustable on 3 axes
• Audio connection: USB-C (Quest 3S compatible, no jack needed)
• Certification: Made for Meta
• Warranty: 18 months
• Manufacturer ref.: KW-QA05B-SPF