KZ AZ09 Bluetooth 5.2 Module Wireless Waterproof Ear Hook Extra Long Battery Life Bluetooth Cable for ​KZ ZST/ZSTX/ZS10/AS06/AS10/BA10/ZSR/ES4 (B pin)

These work perfect with the KZ ZST iems. They are light and comfortable and stay even with head shaking. Sounds just as great as plugging in with an audio jack. The case is on the large size, definitely have to throw the case in a bag unless you don’t mind bulging pockets. The case also fits with the iems attached. Very happy with this purchase.

Only dislike is when changing songs using the button. The voice telling you that it changed is super compared to music, it's a loud beep super annoying. Other than that battery life is pretty good, connect to my galaxy with no problem

These bluetooth adaptors work very well to turn in-ear monitors into amazing wireless earbuds. I had no issues pairing them to my MacBook. The battery life is really good, and the case only needs recharging every 10 days or so.Two small caveats that cost them a star for me: 1) one of the pair is a bit loose in the connection. Not super loose, but the monitor will unplug if you put too much pressure on the connection and 2) that same hook can be a little finicky seating down in the case to charge. That really only happened once, but partly because ever since it did I'm very careful to make sure it is well seated in the case.But combining these with a decent set of monitors will give you sound quality you'll never match with any regular earbud. Definitely worth the price.

I bought these as a test to see if I would like the style and fit before dropping $80 or more on a good pair. Connection is awesome, regular earbuds don't connect for me from the interference in my environment, these are a solid connection that hasn't failed or dropped out once. They are more comfortable that I would have thought. The battery life is great, like in excess of 8 hours for me. The volume could be a little more as they seem underpowered sometimes. There have been a couple of times that I wished I could turn them up a little more but they were already all the way up. With BASN iem's the sound is fine with no buzzing or hissing in the background. For my purposes I can't justify buying a more expensive pair just for the louder volume. It wasn't like it wasn't loud enough to hear, just wanted a bit more. After more than a dozen pairs of wireless earbuds($30~$120) that wouldn't keep a connection more than 5 seconds without dropping signal these are the best listening experience I've had. Way better than expected.

Although this is a 78mm 2-pin Bluetooth adapter, it does not fit HEXA!It is very loose when connected to HEXA.However, it does connect to EA500. So, be aware if you want to purchase for your IEM.Secondly, when it connects to the PC, it automatically recognizes it is a hang-free device and a hang-free device has a horrible sound. You have to do a little disable/enable in the Bluetooth setting. And that is a little trouble to do so. But you can definitely find instructions on YT.Finally, it is kind of annoying whenever you need to connect to a phone or PC, you will need to put the IEM back in the box. Otherwise, it won't recognize.Besides all these little things, this Bluetooth adapter is very good. The sound is a little lower than connecting with cable, but if you connect to a large volume IEM such as EA500, that problem is solved perfectly. The sound quality is good.Overall, I am very happy with this purchase.Updated: It is dead in 2 two days with the right ear module not charging. And I already threw the box away, so I cannot return it.Do not buy it, I repeat, Do Not Buy It!!

This is a frustrating product. Especially when compared to something like the Shure TW2s.The build quality of the adapters themselves seem solid. The case feels pretty cheap, with the lid hinge in particular seeming like it could easily be damaged if dropped while open.The battery life seems on par with other Bluetooth adapters and the sound quality via AAC also seems sufficient, though support for AptX HD or LDAC is an obvious omission.Charging is nearly always a chore. Pogo pins once again prove their unreliability. I have maybe a 15% chance of both adapters shutting down and entering charge mode on the first try. Taking the adapter out of the charge case and cleaning the pins and pads seems only mildly effective. The only solution I've seen for this is to watch the bluetooth connection on whatever device the adapters are paired to and wait for the connection to break, which signals that both adapters are finally charging.The trick I've found to work around this flaw is to simply shake the closed charge case from side to side until the connection drops. The downside to this is that if you're carrying the adapters with you in a bag, they'll often lose their charge connection when jostled and reconnect to your phone when you're not expecting it. If this happens in a call, it's incredibly annoying.Where the true frustration really comes into play is in pretty much every aspect of software and firmware. They have no adjustment for the impedence of the attached IEMs and every sound and voice prompt is LOUD AS HELL. Using Linsoul KZ ZS10 Pros with a healthy 24ohms of impedence, the poorly enunciated English prompts jolt me every time. The "low battery" prompt begins at 30% and it's repeated so often (and so loud) that the adapaters immediately become unusuable until they're recharged.Switching between different devices is a catastrophe. The AZ09s will not switch devices when externally requested, something that every other bluetooth device I've used will do without complaint. They must be in pairing mode before they will even attempt to connect to something else, regardless of whether or not it's been paired before.This wouldn't be a deal breaker except for another of the software's flaws: there is no way to command the adapters to enter pairing mode. This is a baffling omission. The only way to get the adapters to go into pairing mode is to disconnect them from the device side. Forget to disconnect them from your PC before you left the room intending to connect them to your phone instead? You have no choice but to go back to your PC and explicitly disconnect them before they will allow your phone to request a connection. For anyone who switches their Bluetooth adapters between devices multiple times per day, this could easily be a deal-breaker.The adapters flash their too-bright blue LEDs every four seconds when in standard run mode. Why? I have absolutely no idea. They could have made that interval three times as long and it would still serve to signal that the adapters are powered on perfectly well.The voice prompts have the absolute bare minimum attempt at English. I refuse to believe that the designers couldn't fine a single person with a passable accent. It feels, like with many other aspects of the software/firmware, that they simply didn't care.With the newish Qualcomm SOC doing pretty much all the heavy lifting, the lack of any sort of polish software-side is a shameful waste.With no bundled app (which I'm sure would still be a minimum-effort affair anyway), there's no hope for firmware updates to address any these issues.The only aspect that redeems this product is the price. At $30, they're good enough. Unfortunately, they're also the best adapters available for the terrific range of 2-pin Chi-Fi IEMs currently on the market.

Works good. Nice range and sounds