Garmin Pro Heart Rate Monitor Physical Specifications Unit dimensions (LxWxD): 23.5"-56.0" x 1.2" x 0.5" (60.0-142.0 x 3.0 x 1.2 cm) Weight: 2.1 oz (59 g) Module size: 29.4 x 51.4 x 8.5 mm Module weight: 1.7 oz (49 g) Size adjustment: Bi-fold Sizing range: 23.5"-42.0" (60.0-106.0 cm); 23.5"-56.0" (60.0-142.0 cm) with optional strap extender Battery: CR2032 Battery life: 12 months (Tri training 1 hour per day) Water rating: 5 ATM Operating temperature: 14°F-122°F (-10°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 Additional ANT+® heart rate: yes BLE heart rate: yes Supports heart rate variability and advanced heart rate features: yes ANT+ running dynamics: yes Stand-alone activity monitoring (steps, all-day heart rate, calories and intensity minutes) Support Physio TrueUp Stores and forwards heart rate: yes Swim interval heart rate statistics: yes https://buy.garmin.com/en-US/US/p/682155#specs