Techno Line WT 768 Instruction Manual page 21

Do not expose the unit to extreme temperatures, direct sunlight, dust
or humidity.
Do not immerse in water.
Avoid contact with any corrosive materials.
Do not dispose this unit in a fire as it may explode.
Do not open the inner back case or tamper with any components of
this unit.
Batteries safety warnings
Use only alkaline batteries, not rechargeable batteries.
Install batteries correctly by matching the polarities (+/-).
Always replace a complete set of batteries.
Never mix used and new batteries.
Remove exhausted batteries immediately.
Remove batteries when not in use.
EN9