How We Research
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-03 · 7 min read · Independent comparison
• Monster Open Ear AC339 — biggest strength: up to 40 hours of playback paired with a smart digital display that shows the remaining battery level, plus Bluetooth 6.0 and IPX6 water resistance.
• Monster Open Ear AC339 — biggest trade-off: it uses a clamp-over clip design in silicone, which some people feel as pressure on the ear over very long sessions, and it has no noise control of any kind.
• SARUNN ER Open Ear Headphones — biggest strength: memory-foam earhooks you can angle to your own ear shape, a 10-hour single-charge runtime that stretches to 40 hours with the case, and environmental noise cancellation for calls.
• SARUNN ER Open Ear Headphones — biggest trade-off: lower IP55 water resistance than the Monster pair, and its wireless connection is the older Bluetooth 5.3 generation.
• Who each pick is for: the Monster AC339 suits someone who wants to charge rarely and always know how much power is left; the SARUNN ER suits someone who wants an adjustable, glasses-friendly fit and quick top-ups between workouts.
The AC339 is built around two ideas: sound that stays clear without plugging your ears, and a battery you never have to think about. The headline figure is up to 40 hours of playback, and Monster pairs that with a smart digital display so the remaining charge is visible instead of a mystery. If you have ever had a pair of buds die mid-commute because you guessed wrong about the battery, that readout is the feature you will actually use every day.
The fit is a clamp-over, open-ear clip design with silicone ear pads, so the bud sits against the outside of your ear rather than inside the canal. That keeps you aware of traffic, training partners and office chatter. Controls are touch-based and cover the usual jobs — answer and end calls, summon a voice assistant, play and pause, skip tracks — which matters when your hands are busy driving, running or lifting. Bluetooth 6.0 is the newer wireless generation here, and IPX6 means strong jets of water from any direction are not a problem, so sweat and rain are covered.
Who should buy it: anyone who wants maximum time between charges, a visible battery indicator, and a secure clip-on hold for workouts and commutes. Who should skip it: if you specifically want earhooks that loop around the ear, or you want noise cancellation on calls, look at the SARUNN instead — the AC339 lists no noise control at all, and its silicone clamp is a different feel from a memory-foam hook.
The SARUNN ER takes the opposite approach to fit. Instead of a clamp, it uses lightweight memory earhooks, and the angle of each bud can be adjusted to match your ear shape. That is a real advantage if you wear glasses, because the hook sits around the ear rather than pressing against the arm of your frames. The enclosure combines ABS with memory foam, and the whole point of that combination is no pressure or pain after long wear.
On the spec sheet, the buds are rated for 10 hours of continuous use on a single charge, extended to 40 hours total with the portable charging case. The case carries an LED power display for both the remaining battery and the charging status of the buds. Charge time is listed at just 5 minutes, which tells you the case is designed to hand you a useful top-up fast — the kind of thing that matters if you remember to charge five minutes before leaving the house.
Audio comes from 10.4mm dynamic drivers, tuned to reduce distortion and sharpen accuracy, with a built-in high-definition microphone for calls. The open design keeps you aware of your surroundings, which is the whole reason to wear open-ear buds on a bike or a trail. Environmental noise cancellation helps on the microphone side. Water resistance is IP55, which handles sweat and rain but is a step below the Monster's IPX6. Bluetooth is 5.3. Touch controls handle track switching and the rest.
Who should buy it: runners, cyclists, hikers and gym-goers who want an adjustable hook fit, glasses compatibility, and a case that lives in a pocket or bag. Who should skip it: if you want the latest Bluetooth generation, the highest water rating in this comparison, or a battery readout on the buds themselves rather than the case, the Monster is the better match.
• Best for total battery life → Monster Open Ear AC339. Both reach 40 hours, but the Monster delivers it from the buds themselves, while the SARUNN needs the charging case to get there.
• Best for battery visibility → tie, with a twist. Monster puts a digital display on the buds; SARUNN puts an LED display on the case. Pick based on whether you want the number on your ear or in your bag.
• Best for fast top-ups → SARUNN ER Open Ear Headphones. A listed 5-minute charge time is the standout number in its battery spec.
• Best for glasses wearers and adjustable fit → SARUNN ER Open Ear Headphones. Memory earhooks with an adjustable angle beat a fixed clamp for anyone whose ears or frames need wiggle room.
• Best for the newest wireless generation → Monster Open Ear AC339. Bluetooth 6.0 versus Bluetooth 5.3.
• Best for calls in noisy places → SARUNN ER Open Ear Headphones. It lists environmental noise cancellation; the Monster lists none.
• Best for driver size data → SARUNN ER Open Ear Headphones. Its 10.4mm dynamic drivers are specified explicitly; Monster lists a dynamic driver with a 20 Hz–20,000 Hz range but no driver size.
• Best for touch control as the deciding factor → both qualify, differently. Monster's touch control is framed around hands-free calls, voice assistant and music while driving, exercising or running; SARUNN's is framed around switching tracks and everyday playback taps.
My Verdict
In my opinion, the SARUNN ER Open Ear Headphones are the safer buy for most people, because the adjustable memory-hook fit is the part of an open-ear bud you feel every single minute — and the 5-minute top-up plus the 10-hour single-charge runtime covers a normal week of workouts without much planning. I would pick the Monster Open Ear AC339 instead if battery anxiety is your main gripe and you want the number staring back at you on the bud, along with IPX6 and Bluetooth 6.0. If you wear glasses or your ears have never loved clip-on designs, go SARUNN. If you want the toughest water rating and the newest Bluetooth here, go Monster.
how to disable touch controls on headphones
There is no universal switch, and neither the Monster AC339 nor the SARUNN ER lists a setting to turn its touch controls off — both rely on touch as the primary control method. If stray taps are the problem, the practical fix is to take the buds out when you are not listening, since an open-ear bud resting against your ear can register contact. Check the manufacturer's manual or app, if one exists, for the specific model before assuming it can be disabled.
why are my headphones controlling my phone
Because the touch surface on the bud is sending commands over Bluetooth — play, pause, skip, answer or end a call, or wake a voice assistant. Both the Monster AC339 and the SARUNN ER use touch control, and Monster specifically lists voice assistant and call handling among the functions a single touch can trigger. If your phone reacts when you did not mean it to, that is a touch being registered by contact with your ear, hair or a pocket.
what is touch control on headphones
Touch control means the outer surface of the earbud is a capacitive panel rather than a physical button — you tap or hold it to issue commands. On the Monster Open Ear AC339 that covers answering and hanging up calls, the voice assistant, and music management. On the SARUNN ER it covers sensitive smart touch controls for switching tracks and adjusting playback. Both are button-free by design, which is what makes them convenient while running or driving.
do these open-ear headphones have noise cancellation
The Monster Open Ear AC339 lists no noise control at all. The SARUNN ER Open Ear Headphones list environmental noise cancellation, which works on the microphone side to help call clarity. Neither product removes background sound from what you hear, and that is intentional — the open design is meant to keep you aware of traffic, people and surroundings while you listen.
As an Amazon Associate I earn from qualifying purchases.
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
When you buy through links on this page, we may earn a commission from qualifying purchases at no extra cost to you.
Amazon and the Amazon logo are trademarks of Amazon or its affiliates. This site is an independent third-party review and is not affiliated with, endorsed by, or sponsored by Amazon or the product brands mentioned.
See also: ergonomic earbuds, SABRENT USB External vs VYVIYON 6.0, OYEALEX Active Noise Cancelling vs JOYWISE Headphones, XKDUN Open Ear Headphones vs SANOTO Bone Conduction Headphones