UEi Test Instruments UTL7002 - Manual (Page 3)

Battery Replacement
If the visual and audio signals become weak, the batteries should be
replaced. Slide out battery door located on the back of the Detector
and insert two fresh LR44 button batteries (UEi #B13), making sure of
correct polarity. Replace battery cover.
Always use a fresh replacement battery of the specified size and type.
Immediately remove the old or weak battery from the meter and
dispose of it in accordance with your local disposal regulations. Old or
defective batteries can leak chemicals that corrode electronic circuits.
UTL7002-MAN P. 2