Under Armour39 Chest Strap
SizeOne Size Fits All
BatteryCoin cell battery
Battery life
Water resistanceSweatproof
SensorHeart rate sensor
Internal storage120 days
Heart rateYes
Heart rate variabilityYes
Running metricsNo
Swim statisticsNo
OtherStores biometric info—including heart rate, calories burned, real-time intensity, and WILLpower™—and transmits it automatically in real time to the MapMyFitness apps, Armour39 app, or Watch
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