Excellent heart rate monitor if you want something simple, relatively inexpensive and easy to use. It comes with a belt which is coded, so it will only measure your own heart rate and not somebody elses if you're training together. By shortly keeping the watch close to the belt you can switch between showing your heart rate, duration of your training and the current time. It stores the average and maximum heart rate and duration of one training in its memory, so you will have to write it down if you want to keep a training log. It is waterproof.
Be aware that the battery of the belt cannot be replaced, so you will have to replace the entire belt if the battery runs down. The manual states avarage battery life is about 2500 hours though, so it probably won't run down very quickly.