The Suunto M2 heart rate monitor is a mid-level HRM that comes with all the basic features needed, plus some very handy additions that make it easier for you to adjust your training intensity during a workout session. The more flexibility you have the better your outcomes will be.
This is done by giving you feedback about which one of three heart rate zones you are currently in. Based on this feedback which is given both visually and through sounding a beep, you can either increase or decrease the intensity at which you are training. This allows you to optimize your progress to higher fitness levels.