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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
• ZEYARUIBO Earbuds – biggest strength: A sealed in-ear design with active noise cancellation, 14 mm dynamic drivers, and up to 48 hours of total playtime (8 hours per charge plus six case recharges).
• ZEYARUIBO Earbuds – biggest trade-off: In-ear buds physically block your ear canal, so you hear less of the world around you — not ideal if you want to stay aware on a busy road.
• Monster Open Free AC100 – biggest strength: An open-ear hook design with 16 mm drivers and AI noise-cancelling dual mics that keep your ear canal open and pain-free for hours.
• Monster Open Free AC100 – biggest trade-off: Shorter total battery (30 hours, 6 hours per charge) and no sealed fit, so bass depth and isolation depend heavily on how the hooks sit on your ears.
• Who each pick is for: ZEYARUIBO for focused listening, commuting, and long sessions where you want sound to yourself; Monster Open Free AC100 for runners, cyclists, and anyone who wants music without plugging their ears.
The ZEYARUIBO Earbuds are built around one idea: keep the sound in and the noise out. They sit in your ear as a bud-style in-ear headphone with active noise cancellation, so the seal does two jobs at once — it locks in the low end from the 14 mm dynamic drivers and it physically blocks some of the world. That's the classic trade-off of this style, and ZEYARUIBO leans into it deliberately.
The spec that stands out most is battery. Each earbud is rated for up to 8 hours of playtime, and the charging case can refill them roughly six times for a total of up to 48 hours. A full charge takes about 90 minutes over USB-C. In practice that means you can leave the case at home on a long travel day and not think about charging once. Bluetooth 5.3 keeps the connection steady with a rated range of about 33 feet, which matters in crowded places like subways and shopping centres where older chips tend to stutter. The buds themselves are light — 0.13 oz each — and the sound is tuned across a 20Hz–20,000Hz range with a 32-ohm impedance, with adjustable sound modes if you want to nudge the profile toward bass or vocals.
Buy it if you want a sealed, noise-cancelling in-ear for commuting, studying, or working in a noisy room, and you value not charging constantly. Skip it if you need to hear traffic, coworkers, or announcements while you listen, or if you simply don't like anything sitting inside your ear canal. The IPX7-rated water and dust protection covers sweat and rain, but comfort is the deciding factor here, not durability.
The Monster Open Free AC100 does the opposite by design. Instead of sealing your ear, it rests on it — an open-ear headphone with earhooks that sit outside the canal. Monster's whole pitch is that air circulates freely, so your ears don't get sore or sweaty even after a full day of listening. That's not marketing fluff; it's the fundamental physics of the category. Nothing presses on the canal, so nothing irritates it.
The drivers are actually larger than the ZEYARUIBO's at 16 mm, and the tuning covers the same 20Hz–20,000Hz range. Big drivers in an open shell are how Monster gets a wide soundstage without a seal. On calls, the AI noise-cancelling with dual microphones monitors your surroundings and produces an opposite signal to cut background noise, which is the part that matters most if you take meetings from a café or a busy office. Battery is rated at up to 6 hours per charge and 30 hours total with the case — enough for a week of workouts, but noticeably less headroom than the in-ear option. Bluetooth 5.3 handles the pairing and connection, and there's a water-resistant nano-coating for sweat and rain splash.
Buy it if you run, cycle, lift, or commute on foot and want to hear sirens, cars, and people while your music plays. Skip it if you need deep isolation for noisy flights, want the longest possible battery between charges, or prefer the tighter, thumpier feel of a sealed bud. The open design is the entire point — and the entire compromise.
• Best for total battery life → ZEYARUIBO Earbuds. Up to 48 hours total versus 30 hours on the Monster.
• Best for single-session endurance → ZEYARUIBO Earbuds. 8 hours per charge against 6 hours on the Monster.
• Best for situational awareness → Monster Open Free AC100. The open-ear design lets traffic and ambient sound in by design.
• Best for noise isolation → ZEYARUIBO Earbuds. Active noise cancellation plus a sealed in-ear fit beat an open shell.
• Best for long-wear comfort if you hate in-ear pressure → Monster Open Free AC100. No ear-canal insertion means no soreness after hours.
• Best for bigger drivers and a wider soundstage → Monster Open Free AC100. 16 mm drivers versus 14 mm.
• Best for calls in noisy places → Monster Open Free AC100. Dual mics with AI noise reduction target voice pickup specifically.
• Best for workouts where sweat and rain are a factor → either, with a caveat. ZEYARUIBO claims IPX7 protection; the Monster uses a water-resistant nano-coating.
In my opinion, most people shopping this pair should buy the ZEYARUIBO Earbuds. The 48-hour total battery, active noise cancellation, and sealed in-ear fit make it the more versatile everyday headphone for commuting, work, and study — and the 8-hour single charge is genuinely useful. I'd only steer you to the Monster Open Free AC100 if hearing your surroundings isn't optional for you: runners, cyclists, and anyone whose ears ache after an hour of in-ear pressure. That's a real need, not a minor one, and for that buyer the open-ear design is worth giving up battery life and isolation.
The ZEYARUIBO Earbuds. They're rated for up to 8 hours per charge and up to 48 hours total with the case, versus up to 6 hours per charge and 30 hours total for the Monster Open Free AC100.
Are the Monster Open Free AC100 good for running?
They use active noise cancellation combined with an in-ear seal, which is the most effective combination in this comparison for cutting background sound. That same seal is why they're a poor choice if you need to hear traffic or conversations while listening.
I don't quote prices here — they change often. Check the current price on Amazon using the button on this page, then weigh it against what you actually need: maximum battery and isolation (ZEYARUIBO) or open-ear awareness and long-wear comfort (Monster Open Free AC100).
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