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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
If you want long listening sessions with a traditional over-ear fit and wired backup, choose RORSOU B8; if you need a waterproof, phone-free headphone built for swimming and sweaty training, choose Monster Open Ear BC300. These two look like they compete for the same "workout audio" shopper, but they're built for completely different days. One is a foldable over-ear headphone with a huge battery and a 3.5 mm jack. The other is a bone-conduction open-ear set that can go underwater. In my opinion, picking between them is less about which is "better" and more about whether you're sitting at a desk or standing at the edge of a pool.
• RORSOU B8 biggest strength: 50-hour battery life, 40 mm dynamic drivers, Bluetooth 5.4 plus a 3.5 mm wired jack — a rare combo at this tier.
• RORSOU B8 biggest trade-off: Over-ear design with sound isolation only, so no waterproofing and nothing that keeps it stable during hard training.
• Monster Open Ear BC300 biggest strength: IPX8 waterproofing with a 32GB MP3 mode, so you can swim with music and no phone nearby.
• Monster Open Ear BC300 biggest trade-off: Only 10 hours of playtime, bone-conduction sound leaks by design, and there's no wired jack at all.
• Who RORSOU B8 is for: commuters, students, home and office listeners who want one headphone that lasts days.
• Who Monster Open Ear BC300 is for: swimmers, runners and cyclists who need water protection and awareness of traffic.
The RORSOU B8 is a classic over-ear headphone, and the spec sheet makes no secret of it. You get oval ear cups over a 40 mm dynamic driver, an ABS/metal/PC build, and a folding frame that tips the scale at 0.23 kg. That's light for an over-ear, which matters if you wear headphones for hours at a desk, on a plane, or through a long study session. Bluetooth 5.4 gives you a 10-meter working range, and there's a 3.5 mm jack waiting for the moment your battery dies or you want zero-latency audio for a video call or a game.
The headline number here is the 50-hour average battery life, with a 2-hour charge time. In practice that means you can leave the charger at home for a week of commuting and still not think about it. RORSOU also lists 6 EQ music modes, so you can nudge the tuning toward more bass, more vocals, or something flatter without touching an app. With 32 ohm impedance and a dynamic driver, these are easy to drive from a phone, tablet, laptop or PC — the kind of headphone you can plug into anything and forget about.
Who should buy it: anyone whose listening happens mostly indoors or on the move through normal life — work, school, travel, tablet and PC use. The over-ear cups and sound isolation mean you get some passive quieting of the room around you, which is exactly what you want on a noisy train but exactly what you don't want on a bike lane.
Who should skip it: swimmers, and anyone who trains hard enough to sweat heavily. There's no waterproof rating in the specs, no memory frame, no ear hooks. Get these wet or soak them and you're gambling. If your workouts are the main event, this isn't the pair. Also skip if you specifically want to hear your surroundings while listening — sound isolation works against you there.
The Monster Open Ear BC300 is a different animal entirely. It's a bone-conduction, open-ear design built on a flexible memory frame with soft silicone ear hooks. Nothing goes inside your ear canal, so your ears stay open to traffic, training partners, and whatever is happening around you. That's the whole point of the open-ear format, and Monster leans all the way into it.
The defining feature is IPX8 waterproofing. Monster states it's protected against sweat and can be submerged up to two meters for two hours — and crucially, notes that underwater listening happens in MP3 mode, because Bluetooth simply can't transmit reliably through water. So the 32GB of built-in storage isn't a gimmick; it's the mechanism that makes pool swimming possible at all. Monster says that storage holds up to 8,000 songs, transfers over USB, and that you can sort tracks into folders and switch between them on the device. It also remembers your last playback position, which is a small thing that matters a lot when you're mid-set and don't want to restart an album.
On the wireless side you get Bluetooth 6.0 with a 33-foot range, button controls, and no active noise control at all — which is intentional for safety. Battery life is listed at 10 hours with a 2-hour charge via a magnetic charging cable. Monster specifically calls out corrosion-resistant charging contacts, which is the kind of detail that tells you they expected pool and saltwater use. The memory frame is adjustable, so smaller heads can reshape it for a secure fit under swim caps, goggles or a bike helmet.
Who should buy it: lap swimmers, open-water swimmers, runners, cyclists, and gym-goers who want music without blocking the world out. Anyone who wants to leave the phone in a locker and still have 8,000 songs available.
Who should skip it: people who want deep, isolated sound. Bone conduction trades bass depth and isolation for safety and water resistance — that's physics, not a flaw. If you mostly listen on planes or in noisy offices and want to block everything out, the open-ear format will disappoint you. Same if you want a wired fallback: there's no jack here.
• Best for battery life → RORSOU B8. 50 hours versus 10 hours is not close. If charging is your annoyance, the B8 wins outright.
• Best for swimming and water → Monster Open Ear BC300. IPX8 plus 32GB MP3 mode is the only way either of these works in a pool.
• Best for commuting and travel → RORSOU B8. Over-ear cups, sound isolation, folding frame, and a 3.5 mm jack for in-flight entertainment systems.
• Best for running and cycling → Monster Open Ear BC300. Open-ear design keeps you aware of traffic, and the memory frame stays put.
• Best for phone-free listening → Monster Open Ear BC300. 8,000 songs on board, no phone required.
• Best for desk, study and PC use → RORSOU B8. Wired or wireless, 10-meter range, and a light 0.23 kg build for long sessions.
• Best for EQ flexibility → RORSOU B8. 6 EQ music modes give you tuning options the BC300 simply doesn't offer.
• Best for hot, sweaty workouts generally → Monster Open Ear BC300. Sweat protection and a secure fit beat isolation every time here.
In my opinion, the right answer depends entirely on where you'll wear them, so I'll commit: I'd buy the Monster Open Ear BC300 if training is the reason I'm shopping, because IPX8 waterproofing and 32GB of offline music are things the RORSOU B8 cannot do at any setting. But if my listening is mostly commuting, work and travel, I'd buy the RORSOU B8 without hesitation — 50 hours of playtime, a wired jack, and an over-ear fit make it the better everyday headphone. Two different jobs, two different winners.
FAQ
Yes. It runs Bluetooth 6.0 with a 33-foot range for normal wireless use. You only need to switch to the 32GB MP3 mode when you go underwater, since Bluetooth can't transmit reliably through water.
They're built differently, so it's not apples to apples. The B8 uses 40 mm dynamic drivers with sound isolation and 6 EQ modes, which suits immersive listening. The BC300 uses bone-conduction drivers with no isolation, which favors safety and awareness over depth.
If "everything" means commuting, work and travel, I'd pick the RORSOU B8 for its battery life and wired option. If it means swimming and outdoor training, the Monster Open Ear BC300 is the only one of the two that fits. Check the current price on Amazon for each before deciding, since that can shift the value calculation.
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