NF-8261. The working temperature of this Cable Locator is 0-40°C (32-104°F). 2. To avoid damage , this device should be protected against excessive mechanical vibration during handling or use, especially dropping. 3. Only professionals are allowed to calibrate and repair this instrument. 4. Prior to usage, inspect the instrument and the test lead in use for external damage. Please ensure that the instrument and the test lead in use are intact. The instrument should not be used unless all the functions of the instrument are well prepared for work. 5. When using the instrument, the rated voltage of the tested line should not exceed the rated voltage specified in the technical specifications of this Cable Locator. 6. Keep the instrument off direct sunlight to ensure perfect functioning and long service life. 7. If the instrument is subject to an extremely high electromagnetic field, its functioning ability may be impaired. 8. Only use batteries as described in the technical data section. 1) Before using a locator that has been placed or transported under extreme climate conditions, please place it under a new favorable environment for a certain period. 2) When the transmitter is connected with live mains , if the Grounding hole of the transmitter is connected with protective ground phase, the current leakage (if any) in the power supply line may join the circuit current of the transmitter, leading to tripping of the leakage circuit breaker, i.e. tripping of FI/RCD. 3) Please maintain the original package well for later mailing (such as for calibration of the instrument).