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