We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-18 · 7 min read · Independent comparison
If you want a proven, no-nonsense bone conduction headset for gym sessions, runs and rides, choose MASTJUST Bone Conduction Headphones; if you need longer battery life, a newer Bluetooth generation and a lighter sound-leakage profile for all-day wear, choose Gelecek Open-Ear. Both are open-ear, bone conduction designs that keep your ears free to hear traffic and gym announcements — the real decision comes down to battery, connectivity and how much weight you want on your head.
• MASTJUST biggest strength: IP65 water resistance plus a 33-foot Bluetooth 5.0 range and a titanium headband that bends 360° without deforming — a genuinely sport-proof build.
• MASTJUST biggest trade-off: Around 8 hours of playtime, no fast charging support, and the manufacturer explicitly warns against using fast-charge cables or adapters.
• Gelecek biggest strength: Up to 10 hours of battery life, Bluetooth 5.4, Type-C fast charging and a claimed 50% reduction in sound leakage thanks to a fully enclosed cavity.
• Gelecek biggest trade-off: IP55 is the lower water-resistance rating of the two, and the titanium frame carries a bit more weight on paper (29 g vs 24.95 g).
• Who MASTJUST is for: Sweaty outdoor athletes who want maximum splash protection and a featherweight fit.
• Who Gelecek is for: Commuters, remote workers and long-session users who want more hours, newer Bluetooth and less audio bleed.
The MASTJUST set is built around the idea that a sports headphone should survive the workout. The IP65 rating is the headline here — that's protection against water splashes and heavy sweat, which is exactly the failure point for most cheap earbuds after a few weeks of training. The manufacturer is upfront that it is not for swimming, so treat this as a land-sports device: running, hiking, cycling, gym work, driving with one ear on the road.
The physical design backs that up. A memory titanium alloy headband that can bend 360° without deforming is the kind of detail that matters if you stuff your headphones into a gym bag every day. At 24.95 g it's the lighter of the two, and the silicone enclosure with sponge earplugs in the box suggests the brand is thinking about comfort over long sessions rather than pure audio showmanship. The 8-ohm impedance and bone conduction driver are typical entry-tier sports tuning — expect clear voice and rhythm, not audiophile layering. Bluetooth 5.0 with a 33-foot range is fine for a phone in an armband or a locker across the room; it is not the newest standard, so a busy 2.4 GHz environment may occasionally feel less bulletproof than Bluetooth 5.4.
Skip the MASTJUST if you need marathon battery life, the latest Bluetooth version, or you want to swim. The IP65 rating is for splashes, not submersion, and the brand says so plainly.
Gelecek Open-Ear: Who It's For
Gelecek's pitch is different: it's the headphone for the person who wears it all day, not just for the hour in the gym. Up to 10 hours of battery life is the number that changes behavior — that's a full workday of calls and music, or a long ride with navigation audio the whole way. Type-C fast charging means a short top-up gets you back out the door, which is the opposite experience of a headset that demands a two-hour commitment.
Bluetooth 5.4 is the more current standard of the two, and it's paired with a noise-cancelling microphone for hands-free calls. If you take video conferences or long business calls, that's a real practical advantage over a Bluetooth 5.0 headset — newer Bluetooth generations generally mean better connection stability and power efficiency, though the real-world gap depends on your phone and environment.
The other Gelecek differentiator is the fully enclosed cavity design, which the brand claims reduces sound leakage by up to 50%. Bone conduction's classic complaint is that everyone around you hears your podcast. If you share an office, a train carriage or a quiet apartment, that's a meaningful improvement — take the "up to 50%" as the manufacturer's claim rather than a lab-verified figure, but the design intent is clear. The titanium frame at 29 g is flexible and durable, and the IP55 rating handles sweat and rain.
The trade-off is water resistance: IP55 is lower than the MASTJUST's IP65, so if you're a heavy sweater doing hot yoga or you ride in downpours, the MASTJUST has the edge. Despite the product title mentioning swimming, the spec sheet lists IP55 — don't read that as a pool-ready rating. Skip the Gelecek if your priority is maximum splash protection and the lightest possible fit on your head.
• Best for battery life → Gelecek Open-Ear. Up to 10 hours vs roughly 8 hours on the MASTJUST.
• Best for water and sweat protection → MASTJUST Bone Conduction Headphones. IP65 beats IP55, and IP65 is the stronger splash/sweat rating of the two.
• Best for calls and remote work → Gelecek Open-Ear. Bluetooth 5.4 plus a noise-cancelling mic for hands-free calls and video meetings.
• Best for the lightest fit → MASTJUST Bone Conduction Headphones. 24.95 g vs 29 g on the Gelecek.
• Best for quiet shared spaces → Gelecek Open-Ear. The enclosed cavity is designed to cut sound leakage by up to 50%.
• Best for charging convenience → Gelecek Open-Ear. It supports Type-C fast charging; the MASTJUST explicitly should not be charged with fast-charge cables or adapters.
• Best for pure outdoor training → MASTJUST Bone Conduction Headphones. IP65, a 360° bendable titanium band and a 33-foot range suit running, hiking and cycling.
• Best for a full day away from a charger → Gelecek Open-Ear. Longer playtime plus faster top-ups means fewer charging interruptions.
I'd buy the Gelecek Open-Ear. Ten hours of battery, Bluetooth 5.4, Type-C fast charging, a noise-cancelling mic and reduced sound leakage cover more of my actual day than a slightly tougher shell does. The MASTJUST is the better pure training headphone — IP65 and 24.95 g are real advantages for sweaty outdoor sessions — but the Gelecek is the one I'd keep on my desk and wear from morning calls through an evening run. If your life is 90% gym and trails and you rarely take calls, flip that recommendation to the MASTJUST. Either way, check the current price on Amazon before you commit, since both sit in a similar budget-friendly bracket.
Both are designed for running. The MASTJUST has the higher IP65 water-resistance rating and a lighter 24.95 g build, while the Gelecek offers 10 hours of battery and Bluetooth 5.4. For long runs, the Gelecek; for the sweatiest, rainiest sessions, the MASTJUST.
No. The MASTJUST is IP65 and the brand states it is not suitable for swimming. The Gelecek is IP55, which covers sweat and splashes but not submersion. Treat both as land-sports headphones.
Bone conduction headphones generally leak some audio. The Gelecek uses a fully enclosed cavity design that the manufacturer claims reduces leakage by up to 50%, so it's the better choice for offices and public transport.
The Gelecek lasts up to 10 hours and supports Type-C fast charging. The MASTJUST lasts up to 8 hours, charges in about 1.5–2 hours, and should not be charged with fast-charging cables or adapters.
Bluetooth 5.0 on the MASTJUST handles a stable 33-foot connection fine for workouts. Bluetooth 5.4 on the Gelecek is newer and paired with a noise-cancelling mic, which is the better setup for calls and video conferences.
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