Because of the recession, I was at first not 100% sure if this product meets my requirements for quality and performance. It is written here often, that there are problems connecting to the chest. These messages I can not confirm. The device is detected on my Tablet Google Nexus 7 (Android 4.4.2) and smartphone Sony Xperia Z (Android 4.3) without any problems. But Please remember: Fully couples first the Bluetooth chest strap with your device, and then configures the fitness app of your choice.
Displayed when you do not equal a pulse, this could possibly be due to the configuration in the fitness app. I had to choose among Runtastic "Runtastic HR Combo Monitor". Then I was able to perform as desired my records.
Conclusion: Have the measured values compared with a pulse oximeter and the heart rate monitor on the ergometer. The values agreed almost always and bear witness to the quality of the product. I recommend to this chest highly enough. It is comfortable to wear and can be configured for some belaibte people. Complicated setting does not exist, as with other products. By me for the purpose of supplementing the App Runtastic a strong buy recommendation. Price / performance ratio for me.