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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
If you want a pair of open-ear headphones you can actually swim in and that play music without a phone, choose Piegricdiat Bone Conduction Headphones; if you need all-day battery, a visibility light for night runs, and the lightest possible fit, choose HAKII Light 2.
• Piegricdiat biggest strength: IPX8 deep-waterproof bone conduction design with a built-in 32GB MP3 player, so you can swim, snorkel or surf with music and no phone nearby.
• Piegricdiat biggest trade-off: Battery life is listed at just 6 hours, and the underwater rating explicitly caps continuous submerged use at under 6 hours.
• HAKII Light 2 biggest strength: A 16-hour playtime rating, a featherweight 26g build, Bluetooth 6.0, and a 180° beacon light string for visibility after dark.
• HAKII Light 2 biggest trade-off: IPX5 only resists sweat and splashes — it is not a swimming headphone, and it has no onboard music storage.
• Pick Piegricdiat if water and phone-free music matter most; pick HAKII Light 2 if long sessions, night visibility and comfort matter most.
This is a specialist tool, and it knows it. The headline feature is the IPX8 rating, which the spec sheet ties directly to swimming, surfing and snorkeling, with a stated limit of no more than 6 hours of continuous underwater use. Bone conduction drivers transmit sound through vibration against the bone near your ear rather than pushing audio into the ear canal, so your ears stay open and you keep awareness of traffic, other swimmers or whatever is happening around you. The frequency range is listed at 20 Hz to 20,000 Hz, and the driver type is bone conduction, not a conventional dynamic driver. That matters: bone conduction has a different tonal character from standard earbuds, and buyers should expect clarity and situational awareness rather than thumping bass.
The second feature is the one people overlook: a built-in 32GB MP3 player. You load songs by connecting the headphones to a computer with the supplied magnetic charging cable, and the headphones show up as a USB drive you copy files onto. Then you switch to MP3 mode and listen with no phone, no Bluetooth pairing and no signal to worry about. For lap swimming, that is the whole point — phones do not go in the pool.
Pairing is handled by Bluetooth 5.3 for wireless use out of the water, with a button control scheme on the earpieces. There is a built-in noise-reduction microphone for calls. The shape is open-ear, the enclosure is plastic in a DeepBlack finish, and the battery is rated at 6 hours per charge.
Who should buy it: swimmers and snorkelers, people who want music in the pool without a phone, runners and cyclists who want to hear traffic, and anyone who dislikes things shoved into their ear canal.
Who should skip it: If you want a single pair of headphones for long training days and evening runs, the 6-hour battery will run out before your day does. And if deep bass is a priority, a bone conduction driver is not the design for that.
The HAKII Light 2 takes the opposite approach: instead of specializing in water, it specializes in the hours around your workout. Playtime is rated at 16 hours, with a 1-hour charge time, which is a completely different category of endurance from the Piegricdiat's 6 hours. It weighs a stated 26g, uses a flexible titanium frame with soft silicone, and the spec sheet leans hard on the comfort argument — no ear insertion, no pressure points, no ear fatigue over a long day.
The safety angle is the second pillar. A 180° "Ultra-Bright Beacon String" offers three lighting modes, which is aimed squarely at night runners and anyone training on roads after dark. The open-ear shape keeps you aware of your surroundings on top of that, so visibility and awareness work together rather than competing.
Audio here is air conduction, not bone conduction, and it uses a 16mm dynamic driver with a stated 135 dB sensitivity and 22 ohm impedance, tuned for what HAKII calls BassBoost low frequencies. In plain terms, this is a conventional driver design pushed for stronger bass than a bone conduction unit typically delivers, with directional audio to limit leakage. Bluetooth is listed as version 6.0 with a 10-meter range, and there are dual AI noise-cancelling microphones for calls plus environmental noise cancellation. You can control it via the on-board buttons or the companion app.
The catch is durability against water. IPX5 means sweat and splashes are fine — rain, hard intervals, a rinse under the tap. It is not a swimming rating, and there is no onboard storage, so you always need a phone or watch connected.
Who should skip it: If you swim, this is the wrong product. If you want music with no phone at all, it has no MP3 mode.
Side-by-Side: Which Should You Choose?
• Best for swimming → Piegricdiat Bone Conduction Headphones. IPX8 covers swimming, surfing and snorkeling; the HAKII's IPX5 does not.
• Best for battery life → HAKII Light 2. 16 hours rated versus 6 hours on the Piegricdiat.
• Best for phone-free listening → Piegricdiat Bone Conduction Headphones. The built-in 32GB MP3 mode runs with no device connected at all.
• Best for night running and visibility → HAKII Light 2. The 180° beacon string with three lighting modes is a feature the Piegricdiat simply does not have.
• Best for call clarity → HAKII Light 2. Dual AI noise-cancelling microphones and environmental noise cancellation versus a single noise-reduction mic.
• Best for bass-forward sound → HAKII Light 2. A 16mm dynamic driver tuned for low frequencies; the Piegricdiat uses a bone conduction driver.
• Best for the lightest, most comfortable long wear → HAKII Light 2. 26g with a titanium frame and silicone, designed for zero ear fatigue.
• Best for hearing your surroundings while riding or running → a tie. Both are open-ear designs; the difference is that HAKII adds the light, and Piegricdiat adds the water rating.
In my opinion, the right answer here is decided by one question: do you get in the water? If yes, buy the Piegricdiat Bone Conduction Headphones. IPX8 plus 32GB of onboard storage is a combination almost nothing else in the open-ear category offers, and it solves a problem — swimming with music and no phone — that the HAKII Light 2 cannot solve at all. If you never swim, I would buy the HAKII Light 2 instead. Sixteen hours of playtime against six, a 26g frame, better call hardware and a beacon light for dark runs is a stronger everyday package for training. Check the current price on Amazon before you commit, then decide based on water, not specs.
Yes — they carry an IPX8 rating, which the spec sheet ties to swimming, surfing and snorkeling. The one caveat is the stated limit: no more than 6 hours of continuous underwater use. That is a long swim by anyone's standard, but it is a limit worth respecting.
No. Its IPX5 rating covers sweat, rain and splashes, not submersion. It is built for running, cycling, gym work and outdoor training in wet conditions — not for the pool or the sea.
No. The HAKII Light 2 has no onboard storage and relies on a Bluetooth connection to your phone or another device. The Piegricdiat, by contrast, stores music on 32GB of internal memory and plays it in MP3 mode without pairing to anything.
The HAKII Light 2, by a wide margin: 16 hours rated versus 6 hours on the Piegricdiat. If you train in long blocks or forget to charge often, that gap is the single biggest practical difference between the two.
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