Klein Tools CL390 Instruction Manual page 9

OPERATING INSTRUCTIONS
CONNECTING TEST LEADS
Do not test if leads are improperly seated. Results could cause
intermittent display readings. To ensure proper connection, firmly
press leads into the input jack completely.
INCORRECT
CORRECT
TESTING IN CAT III MEASUREMENT LOCATIONS
Ensure the test lead shield is pressed firmly in place. Failure to use
the CATIII / CATIV shield increases arc-flash risk.
5/32"
(4 mm)
TESTING IN CAT II MEASUREMENT LOCATIONS
CAT III / CAT IV shields may be removed for CAT II locations. This
will allow testing on recessed conductors such as standard wall
outlets. Take care not to lose the shields.
.7" (18 mm)
9