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 dedicated helmet intercom with rider-to-rider range and marathon battery life, choose TOUCH TWO C9; if you need lightweight open-ear headphones for running, cycling and workouts while keeping your ears aware of traffic and surroundings, choose Acjohtin Open Ear Headphones. These two look similar in a search results page, but they solve completely different problems. One is built to sit inside a motorcycle helmet and talk to a second rider. The other is built to sit on your ears at the gym. Here is how I'd split them.
• TOUCH TWO C9 — biggest strength: A true two-way intercom with a claimed 600-meter (1,970 ft) range between two riders, plus a 1000mAh battery rated at up to 70 hours of music and 120 hours of standby.
• TOUCH TWO C9 — biggest trade-off: It is a helmet-mounted system, not a general-purpose headphone. It also only pairs with the same C9 model for intercom, so both riders need matching units.
• Acjohtin Open Ear Headphones — biggest strength: An open-ear, air-conduction design on Bluetooth 6.1 that leaves your ear canal open, which is exactly what you want for running, cycling and workouts outdoors.
• Acjohtin Open Ear Headphones — biggest trade-off: No active noise control, a narrower 50Hz–5kHz frequency range, and a 16-hour battery that needs 16 hours to charge.
• Pick TOUCH TWO C9 if you ride a motorcycle, dirtbike, snowmobile or ski with a helmet and want intercom, GPS audio and long battery life.
• Pick Acjohtin Open Ear Headphones if you want a light, sweat-friendly open-ear pair for gym sessions and road workouts with ambient awareness.
The C9 is a helmet Bluetooth headset, and everything about it points to that single job. Two 50mm PEN speakers mount inside the helmet, and the kit ships with round and square speaker/microphone adhesive pads, a clip-on base, a wireless unit and two headset-and-microphone sets. That's a system designed to be installed, not worn around your neck. Bluetooth 5.4 handles the connection, and the 32-ohm impedance with a 20Hz–20,000Hz frequency range covers full-range music and voice. There's even a claimed 1ms latency figure, which matters if you're using it for navigation prompts and calls where you don't want a lag between the turn and the voice telling you to take it.
Who should buy it: motorcyclists, dirtbike and snowmobile riders, and skiers who wear a helmet and want intercom, hands-free calls, GPS audio and one-click voice assistant access without leaving the bars. The large push buttons and voice control (Siri and Google Assistant) are designed for gloved hands and eyes-on-road use, and the IPX6 rating means rain and spray aren't an automatic disqualifier. Who should skip it: anyone who wants headphones for the gym, running or casual listening. It's not that product. And if your riding buddy doesn't own a C9, the intercom half of the feature list doesn't apply — the unit only connects to the same model for that function.
Acjohtin Open Ear Headphones: Who It's For
The Acjohtin WS17 is the opposite kind of device: a lightweight open-ear headphone for sport. The open-ear, air-conduction design leaves your ear canal uncovered, so you hear your music and the world around you at the same time. For outdoor running and road cycling, that's the whole point — you're not sealing yourself off from cars, other runners or your surroundings. The housing mixes metal and plastic in a black-and-orange finish, and it runs Bluetooth 6.1 with a listed 10-meter wireless range. There's no headphone jack, which is consistent with the fully wireless design.
On audio, the WS17 uses a dynamic driver with a 50Hz–5kHz frequency range. That's a narrower band than the C9's 20Hz–20,000Hz, and it's worth being honest about what that means: this is tuned for speech, podcasts and the midrange punch of workout music rather than deep sub-bass or sparkling treble detail. There's no active noise control here at all, and the noise control field is listed as none — again, that's the design intent with open-ear, since blocking noise defeats the purpose of staying aware. Controls run through an app rather than physical buttons.
The battery is the clearest trade-off. It's rated at 16 hours of average life, and charge time is also listed at 16 hours. So you get a full workout week out of a charge if you're using them an hour or two a day, but you need to plan the recharge overnight rather than topping up in 90 minutes. The IPX6 waterproof rating matches the C9, which makes sense for sweat and rain. It ships with a protective case.
Who should buy it: runners, cyclists, gym-goers, walkers and anyone who wants open-ear audio with situational awareness and doesn't want a heavy or sealed headphone. Who should skip it: riders who need intercom, anyone who wants active noise cancellation for flights or noisy commutes, and listeners who care about deep bass extension.
• Best for motorcycle, dirtbike or snowmobile riding → TOUCH TWO C9. It's purpose-built for a helmet, with intercom and gloved-hand controls.
• Best for running, cycling and gym workouts → Acjohtin Open Ear Headphones. Open-ear design keeps you aware of traffic and your surroundings.
• Best for battery life → TOUCH TWO C9. Up to 70 hours of music, 50 hours with intercom and calls, 120 hours standby, and a 1.5-hour charge.
• Best for fast charging → TOUCH TWO C9. 1.5 hours to full versus 16 hours on the Acjohtin.
• Best for two-rider communication → TOUCH TWO C9. Real-time intercom and music sharing at a claimed 600-meter range between matching units.
• Best for full-range sound → TOUCH TWO C9. 20Hz–20,000Hz versus 50Hz–5kHz on the Acjohtin.
• Best for situational awareness outdoors → Acjohtin Open Ear Headphones. No noise control and an open-ear fit mean you never block the environment.
• Best for app-based control → Acjohtin Open Ear Headphones. Controls run through an app rather than dedicated helmet buttons.
• Best for buying just one to start → Acjohtin Open Ear Headphones. The C9's intercom value depends on a second matching unit.
In my opinion, these aren't really competitors — they're two answers to two different questions, and the right buy depends entirely on whether you ride with a helmet or train with your ears open. If I had to pick one for myself, I'd take the TOUCH TWO C9, because its combination of two-way intercom, 50mm speakers, IPX6 sealing and that 70-hour-plus battery is a lot of capability packed into one helmet accessory, and the 1.5-hour charge means it's always ready. I'd only steer you to the Acjohtin WS17 if your priority is open-ear awareness for workouts and you're fine with a 16-hour battery and a narrower sound range. Buy for the job, not the category.
FAQ
No. The C9's intercom only connects to the same C9 model. It's not compatible with other brands of Bluetooth motorcycle helmet headsets, so both riders need matching units for intercom and music sharing.
No. Noise control is listed as none, and there's no active noise cancellation. That's intentional for an open-ear design — you hear your music and your environment at the same time.
The TOUCH TWO C9, clearly. It's rated up to 70 hours of music, 50 hours with intercom and calls, and 120 hours standby, with a 1.5-hour charge. The Acjohtin is rated at 16 hours of average life and needs 16 hours to charge. For price and current availability, check the button on this page.
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