BT-3 specification:
Features:

with big LCD display.
Measure and display the indoor/outdoor temperature and indoor humidity
Automatically memorize the Max./Min. values of the indoor/ outdoor temperature and indoor humidity
Show indoor/outdoor temperture and indoor humidity and time at same time.
Switch between / Clock function and alarming function
Body comfort degree display
12/24 hour mode switch
8 minutes snooze function
Recovery function on the Max./Min. values

Technical parameters:
Indoor temperature measuring range: -30°C ~ +50°C(-22∼122)
Outdoor temperature measuring range: -50°C+70°C(-58∼158)
Indoor humidity measuring range: 20%∼99% (Relative humidity)
Resolution: Temperature:0.1; Humidity: 1% RH
Power supply: one 7# alkaline battery
Operation environment: Temperature:0-50C; Humidity: 5%-85% RH.