Works smoothly and does what he should.

The Ultra Sport Navrun Bluetooth 4.0 chest (so the exact name on the packaging) does exactly what you'd expect from such a device, which is to measure the heart rate of its owner.
The installation, if one can speak of such a, is limited to attach the transmitter unit by means of two push buttons on the (scale) belt to load a corresponding app for measuring the heart rate to a suitable smartphone or terminal, and through this contact prepare for chest strap. Bluetooth 4.0 will, however, requires the mandatory smartphone; older phones divorce so categorically.
I have with my Sony Xperia Z1 and a free app right away can make a stable connection to the chest. Crashes I've only while using my Sony SmartWatch 2, then the chest strap draws the short straw - the training so no need to forego SmartWatch.
The belt sits in my good and relatively comfortable without slipping, because he still manages to never over the gentle curve of my belly (as delicatessen vault, beer repository or simply Plauze known) continue to wander down. However, it remains to be seen whether this is also the case when my belly was shrinking through rigorous training.
The consequences of a violent perspiration while exercising can be removed by simple washing of the belt at 40 ° C. First, however, be sure to disconnect the connector from the strap.

Conclusion:
Interested heart rate chest strap, easy to use.