Garmin HRM-Dual Heart Rate Monitor ANT+ and Bluetooth

Module: 2.4" W x 1.3" H x 0.4" D (62 mm x 34 mm x 11 mm)
Strap Length: Adjustable from 25" to 52" (63.5 cm to 132 cm)
Weight: 1.9 oz (54.4 g)
Water Resistance: 1 ATM
Battery: User-replaceable size CR2032 (3 volts)
Battery Life: Up to 3.5 years (based on average use of 1 hour per day)
Operating Temperature: 23°F–122°F (-5°C–50°C)
Radio Frequency/Protocol: 2.4 GHz ANT wireless communications protocol; BLUETOOTH® Wireless Technology 5.0
Range: 3 m
System Compatibility: ANT+, BLUETOOTH