Product Specifications:DimensionsUnit Width (In) - 45 mmUnit Height (In) - 45 mmUnit Depth (In) - 14.5 mmUnit Weight (Oz) - 52 gGeneralBattery Type Rechargeable - internal lithium-ionMemory Capacity - 32 MBSubstance - LeadBattery LifeSmartwatch: Up to 28 days/Unlimited with solar*Battery Saver Watch Mode: Up to 65 days/Unlimited with solar*GPS: Up to 30hrs/48 hrs with solar**Max Battery GPS Mode: Up to 70hrs/370 hrs with solar**Expedition GPS Activity: Up to 32 days/Unlimited with solar**Solar charging assuming all-day wear with 3 hours per day outside in 50000 lux conditions**Solar charging assuming use in 50000 lux conditions"