Editor's Review:
There is a lot of value packed into the S120. This heart rate monitor generally sells for under $100 and comes with lots of features that can help you get more out of your workouts.Most important is the ability to set three target zones. That allows you to set a zone for recovery runs, one for long runs, and one for tempo runs. The S120 will then let you know when you are in or out of those zones.
After your workout the file will tell you how much time you spent in each of the three target zones.
Unfortunately, this HRM does not come with a backlight, so if you run in the dark you may want to consider upgrading to the S210.