If you want replacement tips that can improve fit and passive sound isolation for teachers, choose AZLA SednaEarfit Crystal; if you need a complete wireless earbud set with its own charging case, choose Bloody M70. The first is an accessory for compatible earbuds, while the second is a set of earbuds with Bluetooth connectivity and stated playtime.
AZLA SednaEarfit Crystal vs Bloody M70 at a Glance
• AZLA SednaEarfit Crystal: Hypoallergenic LSR silicone, multiple sizes, and a grippy surface are its strengths; it is only replacement tips, and compatibility depends on the earbud.
• Bloody M70: A complete Bluetooth 5.0 earbud set with a charging case, three sleeve sizes, and stated 22-hour playtime; its key trade-off is that it is an in-ear product, not a replacement tip for another model.
• Choose Crystal if you already own compatible earbuds and want to focus on fit, comfort, and passive isolation.
• Choose M70 if you need wireless earbuds with touch media controls and a charging case.
• For teachers: Crystal suits someone who wants to adjust a compatible pair already in use; M70 suits someone looking for a complete in-ear listening setup.
AZLA SednaEarfit Crystal: Who It's For
The material is German liquid silicone rubber, described as hypoallergenic, with a naturally grippy surface. That combination may appeal to people who find fit and ear comfort more important than adding new playback features. AZLA says the tips are offered in multiple sizes, so buyers can choose among options for different ear shapes. A better-fitting tip can make a pair of earbuds feel more secure in ordinary movement, though fit will vary by person and earbud.
The stated aim is to improve passive sound isolation through an acoustic seal while preserving the earbuds’ original sound signature. That makes Crystal a plausible choice for a teacher who already owns compatible in-ear earbuds and wants to focus on how they sit during planning, commuting, or personal listening. It is not bone conduction hardware, and it cannot turn an existing earbud into a different type of headphone. For someone searching for in ear headphones for teachers, it addresses one part of the experience—the tips—rather than supplying a full set.
Compatibility deserves a careful check before buying. The product information names some compatible earbuds and also lists exclusions, so the fact that a model is wireless or made by a familiar brand does not guarantee a fit. In particular, the information says it is not compatible with Galaxy Buds Pro, Galaxy Buds Live, or AirPods Pro. The 4 mm ultra-short core is described as fitting a wide range of true wireless earbuds, but that is not a promise that every nozzle will work.
Who should skip this: Skip Crystal if you need a complete pair of earbuds, or if you cannot confirm that your earbud model and nozzle are compatible.
Bloody M70 is a complete set of true wireless, in-ear earbuds. Bluetooth 5.0 handles the wireless connection, and the listed transmission distance is up to 10 meters. Pairing is described as selecting “Bloody M70” on a phone. For someone who wants a self-contained set rather than an accessory for earbuds they already own, that is the central difference from Crystal.
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-19 · 8 min read · Independent comparison
The product information gives the M70 a 6 mm M.O.C.I. hybrid diaphragm and lists a 20 Hz–20 kHz frequency range. Those specifications describe its audio hardware and stated range; they do not, on their own, establish how it will sound to a particular listener. The description calls attention to deep bass, while the listing also identifies sound isolation and touch media controls. A buyer choosing it for classroom breaks, commuting, or personal listening should treat it as an in-ear option that seals at the ear, not as an open-ear or bone-conduction design.
The included case is part of the package, and the product title states 22 hours of playtime. The separate product information lists an average battery life of four hours, so those figures should not be conflated: the longer stated playtime refers to the broader setup, while the earbuds’ listed average life is four hours. The listed charge time is 1.5 hours. Bluetooth range and battery figures are useful planning details, but they do not remove the need to recharge the set.
M70 comes with three sleeve sizes—S, M, and L—along with a charging cable and user manual. That gives buyers a few fit options out of the box, though it is not the same as purchasing a broad range of replacement tips. The product title also identifies IPX4, a feature relevant to buyers considering everyday exposure to splashes; it should not be read as a claim that the earbuds can be submerged. The listed control method is touch, and the listed noise control is sound isolation.
For teachers, the practical appeal is that M70 arrives as a complete wireless listening set, rather than requiring an existing pair of compatible earbuds. It may suit someone who wants Bluetooth earbuds for personal use outside instruction hours. It is not presented as a headset with a microphone or classroom communication features, so those needs should not be assumed from the product information.
Who should skip this: Skip M70 if you only want replacement tips for earbuds you already own, or if you specifically need bone-conduction headphones.
• Already own compatible earbuds and want replacement tips → AZLA SednaEarfit Crystal. Bloody M70 is a separate earbud set, not a tip upgrade.
• Want a complete wireless earbud package → Bloody M70. It includes the earbuds, charging case, cable, and three sleeve sizes.
• Prioritize a grippy silicone tip and multiple tip sizes → AZLA SednaEarfit Crystal. Its LSR material and size options are central features.
• Want stated overall playtime and a charging case → Bloody M70. The title gives 22 hours of playtime, while the product information lists four hours of average battery life for the earbuds.
• Want a tip designed to support passive isolation while preserving your earbuds’ sound signature → AZLA SednaEarfit Crystal. The seal depends on fit and compatibility.
• Want Bluetooth 5.0 and touch media controls → Bloody M70. Crystal has no wireless connection or controls of its own.
• Need to choose among S, M, and L sleeves included in a package → Bloody M70. Crystal also offers multiple sizes, but is sold as replacement tips rather than a complete listening kit.
• Looking for the best hifi stereo bone conduction headphones for teachers → Neither product matches that description. Crystal is an earbud-tip accessory, and M70 is an in-ear earbud set.
First, confirm what you are actually replacing or buying. Crystal makes sense only if you have earbuds with compatible nozzles and want different tips. M70 is the choice between these two if you need earbuds themselves, but it does not provide a reason to replace a working pair if your sole goal is changing their fit.
Next, consider how much the fit is part of your decision. Crystal’s silicone tips are described as hypoallergenic and naturally grippy, and the available sizes are intended to accommodate different ear shapes. M70 includes three sleeve sizes. Neither set of size options guarantees a comfortable fit for every person, so a buyer with sensitive ears or a history of fit issues should pay attention to the product’s compatibility and sizing information.
Battery needs also separate the products. Crystal has no battery because it is an accessory. M70 is a wireless device: its title states 22 hours of playtime, while its product information lists four hours of average battery life and a 1.5-hour charge time. If you plan to listen for long stretches, understand which battery figure applies to the earbuds themselves and which describes the broader package.
Finally, think about the listening style you want. Crystal is intended to affect fit and passive sound isolation without changing the original sound signature of compatible earbuds. M70 is a complete in-ear audio product with a listed dynamic driver, frequency range, touch controls, and Bluetooth connection. Neither product is described as bone conduction, and neither should be chosen on the assumption that it is an open-ear design. Check the current price on Amazon if cost is part of your decision.
I would choose AZLA SednaEarfit Crystal if I already owned compatible earbuds and wanted to focus on comfort, grip, and passive isolation. Its value is in improving the fit of an existing setup, not replacing it.
For teachers, I’d make that my pick when the goal is to refine compatible in-ear earbuds for personal listening. If I needed a complete wireless set instead, I’d choose Bloody M70 for its included case, Bluetooth connection, and three sleeve sizes.
No. They are described as compatible with a range of earbuds, but fit depends on the earbud and nozzle. Check the compatibility details for your specific model; the product information names several exclusions.
Yes, the package includes a charging case. The product title states 22 hours of playtime, while the product information lists four hours of average battery life for the earbuds and a 1.5-hour charge time.
Crystal is specifically described as using a seal to improve passive sound isolation while preserving the connected earbuds’ original sound signature. M70 is listed with sound isolation as its noise-control type. The result for either depends on fit.
No. Crystal is a silicone replacement-tip product for compatible earbuds, and M70 is an in-ear wireless earbud set with included sleeves. Neither is described as bone conduction, and neither is listed with memory foam ear cushions.
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