Arrived with a dead battery. Had to order a battery to use. CR2032
Another customer said it eats batteries, so better remove the battery when not in use, and order several at a time.

Update after my trip.  The use is pretty easy, with minor power resets to get past not being ready to use.
I removed the battery holder between use because the first new battery I put in it, was dead within minutes of being turned off.

This turned out to be an issue on my return when I did not remove the battery from the holder (little tricky) and the luggage gorilla threw the batter and holder away.
Not I cannot use it without a battery holder.