Features Digital clock. Large color digits. 12/24 hr. time display with daily alarm. ECG accurate heart rate. Provides estimated calories consumed during exercise session based on heart rate and inputted exercise intensity index. In-Zone goal 0-60 minute count down timer begins countdown once you reach your Target Heart Rate Zone. Heart Rate Target Zone settings in single beat measurements. EZ-Set Target Zone has visual and audible alarms. Target zone can be automatically set to 65% to 85% of max heart rate based on inputted age or can be programmed to user defined values. Shock resistant design. Water resistant to 100 feet. Battery replaceable transmitter belt. Free - Includes an additional watch wristband and battery. ES size - smaller watch face and fits 5" to 8¼" wrist size. Included standard size transmitter belt fits chest size 29½" to 37½" measured just below chest muscles. Optional transmitter strap sizes available: Small size - fits chest size 26" to 29½". Large size - fits chest size 35½" to 53½". One year warranty. Specifications Time: 12 or 24 hour display. Heart Rate Display: 20 - 240 beats per minute. Age Display: 7 - 99 years. Upper Heart Rate Target Limit: 20 - 240 beats per minute. Lower Heart Rate Target Limit: 20 - 240 beats per minute. Maximum Session Kilocalories: 9,999 kcal. In-Zone Goal Countdown Timer: 0 - 60 minutes. Exercise Factor Setting: 0 - 20. Water Resistance to 100 ft / 30 meters. Battery Type Transmitter: lithium CR2050 or CR2032. Battery Type Receiver: lithium CR2032. Battery Life Transmitter: 2.5 years based on 1hr. use daily. Battery Life Receiver: 1.5 years based on 1hr. use daily. Operating Temperature Range: 32°F (0°C) to 122°F (50°C). Watch Buckle: stainless steel. Watch Back Cover: stainless steel. Watch Wristband: polyurethane.