SUNLOG-2B (Bluetooth Data Logger) Features : Range: Temperature: -20 to 60°CHumidity: 0 to 100% RHAccuracy: Temperature: ± 0.2°CHumidity: ±3% RHResolution: 0.01Memory: 30,800 samples.Battery: 3.6V 1/2AA lithiumBattery Life: 6 Months. SUNLOG-2U (USB Data logger) Features : Range: Temperature: -20 to 60°CHumidity: 0 to 100% RHAccuracy: Temperature: ± 0.2°CHumidity: ±2% RHResolution: 0.01Memory: 30,000 samples.Battery: CR2450Battery Life: 4 Months (Depending on Log Interval)