DESC: The Omron HR-100C Heart Rate Monitor is easy to program and a cinch to wear with a ventilated watch band. Knowing your heart rate is important because if you're working out too hard, your activity can actually become counter productive and strain or damage muscles. To achieve an effective workout, no matter what the aerobic activity, you must maintain your heart rate at a proper level for a minimum of 20 minutes. In general, the proper level falls between 65 percent-85 percent of your maximum heart rate. To ensure you don't drop above or below your proper level, the HR-100C is built with an alarm option that indicates low and high heart rates.