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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-17 · 6 min read · Independent comparison
• DUVOSS Open Ear Earbuds — biggest strength: air-conduction open-ear design with big 16.2mm drivers, dual-mic noise cancellation for calls, and up to 10 hours of playback per charge (50 hours standby via the charging case).
• DUVOSS Open Ear Earbuds — biggest trade-off: IPX4 only. It shrugs off sweat and light rain, but it is not built to be submerged, so swimming is off the table.
• FJX Bone Conduction Headphones — biggest strength: IP68 waterproofing plus 32GB of built-in memory, so you can swim with local MP3 playback and leave your phone in the locker.
• FJX Bone Conduction Headphones — biggest trade-off: roughly 4 hours of battery life, no active noise cancellation, and Bluetooth simply doesn't work underwater — you must switch to MP3 mode.
• Who each pick is for: DUVOSS for land-based athletes and commuters who want long listening time and clear calls; FJX for swimmers and water-sports people who need a rugged, phone-free setup.
The DUVOSS S2 is an air-conduction open-ear model, which means the sound is delivered toward your ear without plugging the canal. Flexible silicone cushions and adjustable ear hooks hold the buds in place, and the open structure is what keeps you aware of traffic, gym noise and people around you. If you've ever given up on in-ears because they ache after an hour, the non-invasive fit here is the whole point.
On the audio side, DUVOSS pairs Bluetooth 5.3 with 16.2mm large-diaphragm speakers, a hybrid driver and Liso2.0 bass enhancement, covering a 20Hz–20kHz range. There's also DT3.0 directional sound transmission plus dual-microphone noise cancellation, so calls are a genuine focus rather than an afterthought. Battery is the standout: a 100mAh cell in each bud and a 500mAh case give up to 10 hours of continuous playback and 50 hours of standby, recharged over USB-C. The whole kit weighs 102g and ships in a white plastic case with a cable and manual.
Buy it if you lift, run outdoors, drive, shop or take a lot of calls and want one pair that lasts a full training week between charges. Skip it if your sport happens in the water — IPX4 handles sweat and light rain, nothing more. The control method is app-based over Bluetooth, and there's active noise cancellation listed in the noise-control field, though with an open-ear fit you should expect to stay aware of your surroundings by design.
The FJX AS9 takes a different route entirely. Instead of firing sound at your ear, it uses bone conduction — vibrations sent through your cheekbones to the inner ear — so your ear canal stays completely open. The frame is titanium, weighs just 29g, and hooks behind your ears, which is why FJX pitches it for long runs and swims without swelling or slipping. The earpiece shape is over-ear, and it comes in blue with a fabric carry bag, a charging cable, two special earbuds and an elastic band.
The headline feature is the IP68 rating. That's full waterproofing and dust-proofing, and FJX explicitly says you can swim, snorkel, fish and boat with them on. Because water kills Bluetooth range, the AS9 also carries 32GB of internal storage and runs as a standalone MP3 player — you drag songs onto it from a computer over USB, double-tap to switch modes, and swim phone-free. Triple-tap calls up a voice assistant like Siri. Bluetooth 5.3 handles the dry-land side and pairs with iOS, Android, Mac, PC and tablets.
The trade-offs are real. Battery life is about 4 hours, charged in roughly 1.5 hours, and there's no noise cancellation at all. Underwater you're limited to MP3 mode, and FJX recommends wearing earplugs for better sound while swimming. Buy it if you swim, snorkel or boat and want music without carrying a phone. Skip it if you need all-day battery, noise cancelling, or long conference calls — that's not what this headphone is built for.
Side-by-Side: Which Should You Choose?
• Best for battery life → DUVOSS Open Ear Earbuds. Up to 10 hours playback and 50 hours standby versus roughly 4 hours on the FJX.
• Best for phone-free workouts → FJX Bone Conduction Headphones. The 32GB built-in memory means no phone required at the pool.
• Best for calls → DUVOSS Open Ear Earbuds. Dual-mic noise cancellation and DT3.0 directional transmission are purpose-built for voice.
• Best for light weight → FJX Bone Conduction Headphones. 29g of titanium versus a 102g DUVOSS kit with its charging case.
• Best for all-day wear and commuting → DUVOSS Open Ear Earbuds. Open-ear awareness plus a charging case you can top up on the move.
• Best for water resistance on land only → DUVOSS Open Ear Earbuds. Sweat and light rain are covered; anything deeper is not.
• Best for a rugged, low-maintenance sports companion → FJX Bone Conduction Headphones. IP68 dust and moisture resistance with a two-year warranty.
In my opinion, most people should buy the DUVOSS Open Ear Earbuds. The combination of up to 10 hours per charge, a 50-hour standby case, USB-C charging, dual-mic call clarity and genuinely comfortable open-ear fit covers the way the majority of us actually use headphones — gym, runs, commutes, calls. I'd only steer you to the FJX Bone Conduction Headphones if swimming is your main sport. If it is, the IP68 rating and 32GB of onboard music make the FJX the only sensible pick here, and I'd accept the shorter 4-hour battery as the price of admission. Check the current price on Amazon before you decide, since both are sold there and the gap may matter to you.
No. It carries an IPX4 rating, which covers sweat and light rain. Swimming or submerging it isn't supported. If you need to swim with music, the IP68-rated FJX is the one to look at.
Do the FJX Bone Conduction Headphones work underwater on Bluetooth?
No. Bluetooth signals don't travel well through water, and FJX advises against Bluetooth mode while swimming. You switch to the built-in MP3 player and its 32GB of storage instead, and FJX suggests earplugs for better sound in the pool.
DUVOSS, clearly. It offers up to 10 hours of continuous playback and 50 hours of standby with its charging case. The FJX runs about 4 hours per charge with a roughly 1.5-hour recharge time.
The DUVOSS is the stronger call headphone — dual-microphone noise cancellation and DT3.0 directional sound transmission are designed for voice. The FJX has media controls and can trigger a voice assistant, but it has no noise cancellation and no call-focused features listed.
Both are open-ear designs that avoid plugging the canal. The FJX is lighter at 29g with a titanium frame, while the DUVOSS uses flexible silicone cushions and adjustable ear hooks. For long sessions with music and calls, I'd lean DUVOSS; for minimal weight on a run, the FJX.
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