Etymotic DI-15® High-Definition Electronic Earplugs for Dentists - Manual (Page 6)

Battery Insertion
6
1. The battery compartment
is located on the underside
of the device.
2. Open the battery door.
3. Remove the yellow tab
from the battery.
4. Insert the battery
with the flat side facing up.
5. Do not force the battery
into the door.
Battery
Compartment
#10 Battery
Inserted
Battery
Door