I bought them about a month ago after market research and reading the very good user reviews, primarily for use in sports activities. They connect very easily and quickly with the devices I use, iPhone 7+, Huawei P20 Pro, Garmin fenix 6Xpro, but only with one at a time and not with all (not even with two, but that doesn't bother me at all). I usually use them together with the watch (fenix) listening to music during running or cycling. I haven't experienced any disconnection incidents with the devices, not even momentarily. The build quality is excellent, with many extras in the package including spare ear cushions and 'fins' for every type of ear, with a clip for attachment to the shirt and a carrying case. The sound quality for speech is satisfactory; perhaps in a noisy environment, some may encounter difficulties in hearing, but not to the point where you can't communicate. In music, the sound is excellent, but given that the quality of the music download you have done is equally good. The battery has left me fully satisfied. It lasts about 7 to 8 hours of continuous music listening at maximum volume. For simple speech without music use, it lasts for days. The application now depends on how it fits each person. The headphones feel somewhat 'heavy' with the somewhat bulky speaker and the built-in (and strong) magnet, and at first, you have the feeling that you won't be able to tolerate them for long. It's somewhat like that, but for much longer since they started to slip during running and cycling after about 2 hours of use. For use under a helmet on a motorcycle, they are cumbersome; personally, for safety reasons, I only wear one and only when necessary. However, the earphone inside the helmet, due to its bulk, presses on the ear, and you can't tolerate it for more than half an hour. In conclusion, I am very satisfied, and for the €29 I paid, it was an excellent choice. If your options are within this budget, don't think about it at all.

I studied a lot before purchasing these specific headphones. Although I don't prefer wireless headphones due to sound fidelity and quality transmission of the audio signal. Anyway, due to work requirements, I had to get a Bluetooth headset.
Sturdy construction, super light, sweat-proof or if you splash water on your face (not for diving in the sea), metallic battery compartments, durable cable material with reinforcements at the headphones and the control, strong magnets at the back of the headphones, 3 different pairs of stability ear tips, 4 different pairs of sizes for the buds, and a storage case.
For calls, they are excellent; you hear the other person clearly, and they hear you clearly, the volume is more than enough for calls. Control on the right side, with a microphone on the micro USB side, 2 buttons for volume control, and 1 central button that answers/declines calls. Almost perfect fit in the ears, and they don't come out unless pulled. It's slightly annoying to insert the earbud into the ear canal with those stability tips they have. Of course, those stability tips do a good job. More than 3-4 hours of continuous use in the ears bothers me, especially now that it's hot.
Now let's talk about the sound... Notable detail in sound performance (aptX), rich sound, pleasant medium soundstage, expected from the 6mm drivers and strong low frequencies within reasonable limits. Bassheads will not be left indifferent. All frequencies stand out crystal clear. The mids are lively and pronounced, the highs are harmonic and never screech (even at maximum volume), the bass is incredible for 30 euro Bluetooth headphones, full-bodied and tight without distortions. If a track is downloaded from YouTube, for example, and has poor recording quality, it is extremely annoying in sound when listening through these specific headphones. As I wrote, the sound analysis in music playback is a strong advantage of these. Deadly isolation from external sounds; if you listen to music at 30% volume, you don't hear anything around you beyond a 2-meter radius. As a device, however, it needed about 20%-30% more volume for my taste; it's not a flaw, just that I am a bass lover and want the drums to hit my ears.
The Exclusive BassUp technology that the device has (by pressing the central call button and the volume up button for 3 seconds) is completely useless for my ear. It increases the low frequencies so much, thus noticeably increasing the bass, that it significantly masks the mids and highs.
The 4.2 Bluetooth Class 2, although already outdated, has no trace of delay in audio signal transmission whether it's a video clip or video games. At 12 meters away from the phone in a straight line without obstacles, the Bluetooth does not lose signal. However, it does have some minor interruptions of tenths of a second, regardless of distance (relatively rare). They connect smoothly to Samsung Galaxy S5, connecting to only one device at a time. Switching connections from phone to phone, to laptop or computer takes 2-3 seconds, and when connected to a computer, the battery percentage is also displayed.
In terms of battery, it’s a dynamite for hours... 9 pure hours of continuous music playback at 70%-80% volume, full charge in a maximum of 1 hour and 40 minutes.
For 30 euro headphones, give me some too, uncle! Relatively cheap for what they offer. All-around for all hours, all terrains.

Ποιοτικότατη κατασκευή, απίστευτος ήχος με δυνατό μπάσο, η διπλή λειτουργία ήχου που έχει βοηθάει πολύ αν θες να ακούς κάτι χωρίς πολύ μπάσο. Στο τέρμα το ήχο δεν άντεχα να το ακούσω από το κινητό θα δοκιμάσω και από τηλεόραση να δω πως πάει. Δεν ξέρω αν και πότε λειτουργεί το aptx (κινητό και ακουστικά το υποστηρίζουν) οπότε δεν μπορώ να εκφέρω γνώμη. Δεν πέφτουν σχεδόν με τίποτα από τα αυτιά (συνήθως δεν χρησιμοποιώ in-ear γιατί δεν με βόλευαν) βοηθάνε πολύ τα επιπλέον "αυτάκια" που περιλαμβάνει μαζί με 3 σετ σιλικόνες σε διαφορετικά μεγέθη. Θα επανέλθω για την μπαταρία και αντοχή στον ιδρώτα και νερό. Σε σύγκριση με τα Huawei ΑΜ61 και Creative Outlier Plus έχουν αρκετά καλύτερο ήχο, δεν έχω δοκιμάσει ακριβότερα (>50€) για να έχω άποψη. Γρήγορη σύνδεση σε 3 δευτερόλεπτα, χωρίς διακοπές στη σύνδεση μπορεί και λίγο πάνω από 10 μέτρα ή από τοίχους στο σπίτι.
Πάντως με 2 χρόνια εγγύηση δεν φοβάμαι και πολλά (δεν μου κράτησε ποτέ κανένα ακουστικό πάνω από χρόνο πλην κάτι sony από ένα παλιό κινητό που μετά από 10 χρόνια ακόμα ζούνε).