Easy to monitor heart rate between 30 and 250 bpm within 3 bpm with continuous readout. Comfortable to wear, no chest straps or wires. No disturbance to pacemaker. Optional training mode allows input of personal data with age setting between 6 and 120 years. Display switchable in training mode heart rate and strength percentage cumulative training time average heart rate calories burned cumulatively up to 9999 calories. Set maxmin heart rate limits with display flashing and sound warning for exceeding limits. 12 hour clock. Time keeping capacity up to 99 hours, 59 minutes and 59 seconds. Ambient temperature detection between 32176F and 122176F within 4176F accuracy when not on finger. Powered by one 3V CR2032 lithium battery. Low battery warning. Sizing insert and storage box included. This is not a medical device. One size fits most.