Leica DISTO classic User Manual page 11

Fit batteries the right way round.
7. Insert end cover as shown below.
8.
7.
8. Close end cover carefully.
Must click into place.
Never intentionally hit the end cover
against a hard object - the battery
compartment may be forced open!
To save power, the DISTO switches
off automatically after 90 seconds if
a key is not pressed.
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