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    Sennheiser CX 400 True Wireless In-Ear Headphones - Black

    Was £139
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    Product Overview

    Enjoy music your way with these Sennheiser CX 400BT headphones. They’re wireless, giving you loads of freedom and space to be on the move with your favourite tunes – no time for tangles here. If you sometimes find yourself lost in the moment, the 7-hour battery life means you won’t suddenly be snapped to reality when your music abruptly stops. They’re made by Sennheiser, who are leaders in audio tech, so you know you’re getting headphones that sound amazing and have a sturdy but comfy build. There’s four sizes of ear buds available, meaning you can catch up with old friends you haven’t seen all year or delve into that long audiobook without any earache. For a really unique experience, download the Smart Control app to personalise the sound settings.  

    Key Features

    • Totally wireless design means zero tangled cables
    • Bluetooth connectivity with a 7-hour battery life
    • Decades of Sennheiser expertise and craftsmanship
    • Choose between 4 sizes of ear bud for the perfect fit
    • Use the app to adjust the sound to your taste

    Product Review Video

    Product Review Video

    Product Specification

    Key Information

    Battery Life
    Up to 7 Hours
    Headphone Type
    Microphone Type
    Built-in microphone
    Recommended Usage


    USB Input

    Dimensions Including Packaging

    Depth Including Packaging
    17 cm
    Height Including Packaging
    5 cm
    Width Including Packaging
    12 cm

    Mobile Connectivity

    Mobile App

    Product Detail

    3.5mm Jack
    Country Of Origin
    (H)20.0 x (W)15.0 x (D)10.0
    Sennheiser Expertise
    Series / Family
    CX 400
    CX 400
    Weight With Packaging
    0.202 Kg

    Smart Technology

    Works With Google Assistant

    Sound Technology

    Driver Unit
    True Wireless


    Manufacturer Warranty
    1 Year

    What's In The Box

    Number of Earbuds

    Wireless Connections

    Bluetooth Version

    Features we love

    A front row seat to your dream gig

    These Sennheiser headphones bring you even closer to the music, with studio-quality engineering that’ll blow your mind. Each bud has a specially designed, bespoke audio driver tucked away inside for incredible clarity and a deep, rumbling bass you can really feel. And you can even tailor the experience to your liking with built-in equalisers to get the levels just right. That means when you pop them in, it’ll be like walking around with your very own private concert.

    Premium sound for every device

    Whether you’re jamming to tunes on your phone, or kicking back on the sofa with tablet in hand, these Sennheiser headphones have you covered. They’re made to support a huge range of different devices and codes, including SBC, AAC and aptX. That means however you choose to listen, you’ll always enjoy the same high-quality experience.

    Never run out of power

    These Sennheiser headphones have got plenty of juice to keep you hooked on your favourite playlists all day. The buds themselves have a 7-hour battery life that’ll have you grooving for ages, while the compact case can hold a further 20 hours of charge if you need a top-up. So if you find yourself running low when you’re out and about, they’ll be ready for action again in no time.

    A comfy fit for endless listening

    Lose yourself in the music with the comfort and style of these Sennheiser headphones. They’re specially made to sit snugly in your ear thanks to an ergonomic design, letting you enjoy playlist after playlist without becoming a nuisance. That means you can sit back with good audiobook for hours on end, or enjoy loads of tunes all day long.

    Stay in control

    Pair up your new Sennheiser headphones to any compatible device with the Smart Control app. As well as a quick and easy wireless connection, it also lets you customise just about everything from the bass to how much outside noise you want to hear, which is great when you need to listen for traffic. So, you can pump up the jams at home, or cross the road in complete safety while you’re out.

    Decades of expertise

    Sennheiser have a long history of professional, high-quality engineering and craftsmanship to draw from. For over 75 years, they’ve pioneered some of the most outstanding sound technology designed to give music fans an incredible experience, with crystal-clear highs and deep, rumbling bass. That means you can get fully immersed in your favourite tracks, hear every single note, and really feel the rhythm.

    Customer Reviews

    4.5 / 5
    Showing 4 of 4 reviews

    Very happy

    Purchased after reading a Which Best Buy report and they have not disappointed. Sound quality is great and you can ensure the perfect fit with the additional ear fittings.

    Fantastic product

    Awesome product, definitely recommend for music as I bought it for that purpose. Calls it's a bit tricky as you will be hearing them very clearly but for them the background noise is too much. But as I said for music it's one of the best and I am very happy with it.

    Sounds great but build quality is lacking

    Not bad, but not as expected from a brand like this. Unfortunately doesnt work using just 1 earphone, as my previous ones did. Also the case feels really cheap, light and scratches really easily. Switching between spotify to calls becomes a hassle as you need to manually select audio output.

    Good headphones

    Quick delivery, high quality and good value. Would recommend

    * 508900 was at the higher price between 11/09/2022 and 06/12/2022.

    Intervening prices between the "was" and the "now" price have applied. Intervening prices may have been lower than the current price due to our price match promise or other promotions during the intervening period.

    Any offers are genuine savings. We always want to be able to offer you an incredible deal, so we’ll always match our competitors on price. This means our prices could drop further, or potentially reduce again once a promotional event ends. If our price drops, or you do find what you’re looking for cheaper elsewhere, we’ll offer our price match promise. See terms and conditions.

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