Got the heart rate monitor buy about 2 months ago to my training to monitor anything without disturbing chest. As long as one does not use the clock at the right sporting activities, it actually works properly. And to the weight training, jogging or biking but (slightly) more sweat collects under the clock, measuring no longer works. Only after unbuckle, dry the watch back and wrist (which in the long run rather annoying), can be carried out the next measurement. Until then, however, the pulse then has mostly double-digit calmed down (as compared with the heart rate monitor on the exercise bike). A sweatband next to the clock delay this effect only slightly.
Well, the clock is, however, similar to the pulse sometimes quickly under the work control. Also tell me about the constant pedometer, which allows you to monitor its activities during the day at least approximately (around every now and then in the evening to have a guilty conscience ;-)). When evaluating the two stars are actually too little - but three stars I would not pardon because of the "uselessness" with perspiration - whether the clock in the summer at all useful (except as an ordinary wristwatch), must first show themselves yet.