Garrett Metal Detector GTI 1500 Owner's Manual page 4

Although the GTI 1500 is built to with-
stand rugged treatment outdoors while
giving years of trouble-free service, always
remember that this detector is a precision
electronic instrument.
Protect it from extreme heat and cold as
well as mist, rain or blowing sand. Keep it
as clean as possible.
 - Garrett Metal Detectors