I have a Sony Xperia Z. Suitable for that I had the Sony SmartWatch 2. I was not on price / performance and have been convinced they returned. With this product, I now have something that is not only cheaper, but also better. But the response time of these U8 SmartWatch is worlds better. The connection work right away, it only requires the BTnotification.apk. All Statusmedlungen come across clean, call also works perfectly. What more could you want for the money anyway .....