1. Thermometer and hygrometer are mechanical structure, no battery needed, easy to use
2. The clock is a quartz watch and needs a button battery to power it
3. Small size, easy to place
4. The notch on the bottom of the thermometer can be opened to adjust the position
5. Purpose: temperature measurement, time, air humidity measurement
6. Measuring temperature: -20 to 70 degrees Celsius
7. Material: steel shell, ABS back cover, glass mirror
8. Size: diameter 4cm
9. Weight: about 42g