Garmin G500 Pilot's Manual page 100

Class D Airspace Viewing Range
The Class D airspace viewing range option selects whether Class D airspace
information is shown on the Navigation Map. Class D airspace information
will be shown at and below the selected map range. When Off is selected, the
information will not be shown. In the example below where 150 NM is selected,
Class D airspace information will be shown at map ranges of 150 NM and
lower.
Figure 3-57 Navigation Map Class D Viewing Range Selection
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Garmin G500 Pilot's Guide 190-01102-02 Rev. B