Technical parameters:

Power: DC3V two 7#alkaline batteries for both main unit and extension.
Measuring range:
Main-unit temperature -50 C~+70 C
Extension temperature -9.9 C~+70 C
Accuracy:
Main unit: +-1 C(0 C~+30 C), +-3 C for others
Extension: +-1 C(-20 C~+40 C), +-3 C for others
Resolution: 0.1
Transmission distance: no less than 40M (in the open territory)
Extension numbers: 3

Features:
Switch between cooling, heating and alarming;return difference to control temp.