Well, the alarm is still functioning when the device is 'off'. I'm not sure how long the battery would last in that state but a few days wouldn't be too surprising.
I've kept mine off for a week, bettery level looked like when I switched it off (didn't check the actual numbers).
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Technically, there are three determinate states the cat could be in: Alive, Dead, and Bloody Furious.
Technically, there are three determinate states the cat could be in: Alive, Dead, and Bloody Furious.