We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-20 · 6 min read · Independent comparison
If you want to swim laps with music playing in your ears — no phone nearby, no signal issues — choose MONODEAL Swimming Headphones-IP68; if you need all-day open-ear earbuds for running, lifting and calls on land, choose Anker Soundcore C50i.
• MONODEAL's biggest strength: true IP68 waterproofing with an on-board 32GB music player, so it keeps playing underwater with no phone involved.
• MONODEAL's biggest trade-off: Bluetooth is restricted underwater, so swimming means switching to MP3 mode and managing files yourself.
• Anker Soundcore C50i's biggest strength: long 28-hour total playtime, 12mm drivers, AI-filtered calls and Bluetooth 6.0 for land-based training and commuting.
• Anker Soundcore C50i's biggest trade-off: IP55 only — sweat and rain are fine, full submersion is not — and this listing is a renewed unit.
• Pick MONODEAL if the pool is your main training ground. Pick the Soundcore C50i if you train on land and want longer battery life and stronger bass.
The MONODEAL S820 is built around one problem most headphones ignore: water. The IP68 rating covers immersion down to roughly two meters for up to two hours, and that alone puts it in a different category from ordinary sports earbuds. The catch is physics — Bluetooth doesn't travel well through water, so the company tells you to switch to MP3 mode when you swim. That's exactly why the 32GB of built-in memory matters. You load your albums or audiobooks once, leave the phone in your bag, and the headphones play straight from their own storage. No armband, no locker-room signal dropouts, no phone left on the pool deck.
The design is bone conduction with an open-ear, over-ear fit, which means nothing plugs your ear canal. For swimming that's a real advantage: you can hear lane mates, whistles and the pool ambience while your music plays. It also means the sound reaches you through vibration rather than a sealed driver, so expect a lighter low end than a conventional earbud. The frame weighs 24 grams and uses silicone, so it's meant to sit lightly rather than clamp down. Bluetooth 5.4 handles the wireless side when you're out of the water, and the built-in microphone covers calls. Battery life is rated at 8 hours per charge with a 2-hour charge time, and the frequency range spans 20Hz to 20,000Hz.
Who should buy it: lap swimmers, triathletes in training, and anyone who wants music in the pool or shower without a phone nearby. It also works fine as a normal open-ear headset for running and cycling, where awareness of traffic matters. Who should skip it: if you want maximum bass, ANC-style isolation or the longest possible battery life, this isn't the tool. There's no noise control at all — the open design is the opposite of isolating — and if you refuse to deal with copying files to internal memory, the swimming feature largely goes to waste.
The Soundcore C50i takes the same open-ear philosophy and points it firmly at the gym. The FlexiClip design uses a memory titanium clip that bends to fit your ear shape, and the earbud hangs over the ear without entering the canal. Anker's pitch here is honest about the trade-off: more comfortable than in-ear, better sound than bone conduction. That last part is the core of the C50i's identity — it uses a dynamic driver rather than a bone conduction transducer, so you get a more conventional listening experience.
The numbers back up the land-first design. Custom 12mm drivers push deep bass with up to 86dB output, which is the kind of low-end you simply can't get from a vibration-based driver. Battery life is the headline: 8 hours on a single charge and 28 hours total with the case, and the case recharges the buds in about 1.5 hours. Bluetooth 6.0 is the newest version in this comparison and should mean a very stable connection. AI-filtered microphones handle calls, which matters if you take work calls mid-run or on a commute. Controls are physical buttons rather than touch, which some people prefer with sweaty hands.
The limitation is the IP55 rating. That's protection against sweat and rain — genuinely fine for running, lifting, cycling and outdoor workouts — but it is not designed for swimming or full submersion. One more thing worth flagging: this listing is a renewed unit, so you're buying refurbished rather than new, and the warranty term is shorter than the MONODEAL's one year. It's also the heavier of the two at 44.5 grams total.
Who should buy it: runners, gym-goers, cyclists and commuters who want long battery life, punchy bass and clear calls while staying aware of their surroundings. Who should skip it: swimmers, anyone who wants a new-in-box product, and anyone who prefers a bone conduction fit over a clip.
• Best for swimming → MONODEAL Swimming Headphones-IP68. IP68 with 2-meter immersion for up to 2 hours is the deciding spec.
• Best for battery life → Anker Soundcore C50i. 28 hours total with the case versus 8 hours on a single charge for the MONODEAL.
• Best for bass and loudness → Anker Soundcore C50i. 12mm dynamic drivers rated to 86dB beat a bone conduction driver for low-end punch.
• Best for phone-free workouts → MONODEAL Swimming Headphones-IP68. The 32GB of internal memory means no device required.
• Best for sweat and rain → Anker Soundcore C50i. IP55 is plenty for running and outdoor training; just don't submerge it.
• Best for calls → tie, with a caveat. Both have microphones, but the C50i's AI noise filtering is the more call-focused design.
• Best for situational awareness → either. Both are open-ear and leave your canal unblocked; the MONODEAL does it with bone conduction, the C50i with a clip-on driver.
• Best for a lighter, glasses-friendly fit → MONODEAL Swimming Headphones-IP68. 24 grams and a silicone frame designed not to press on eyewear.
If I were buying for myself, I'd take the Anker Soundcore C50i — because my training is on land, and 28 hours of playtime, 12mm drivers and AI-filtered calls cover far more of my week than a pool session would. In my opinion it's the more versatile everyday pair. That said, the moment swimming becomes a real part of your routine, the MONODEAL wins outright: IP68 and 32GB of built-in memory solve a problem the C50i simply isn't built to solve. Buy the one that matches where you actually sweat. And before you commit, check the current price on Amazon — both sit in different budget brackets depending on the day.
Yes, if you swim regularly. IP68 covers immersion to about two meters for two hours, and the 32GB MP3 mode means you don't need a phone at the pool. Just remember Bluetooth won't work underwater.
No. It's rated IP55, which handles sweat and rain but not submersion. Treat it as a gym, running and commuting pair, not a swimming pair.
On paper the C50i has the edge for bass and volume, thanks to 12mm dynamic drivers rated to 86dB. Bone conduction on the MONODEAL trades low-end weight for open-ear awareness and underwater capability.
The MONODEAL runs about 8 hours per charge with a 2-hour charge time. The C50i also does 8 hours per charge but stretches to 28 hours total with its case, recharging in roughly 1.5 hours.
It's worth knowing before you buy. A renewed unit may show minor cosmetic wear, and the warranty term listed is shorter than the MONODEAL's one year, so weigh that against the longer battery life and stronger drivers.
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