The following image depicts ScaleBar's with different DisplayUnit values set:

Purpose of setting the DisplayUnit Property:

The DisplayUnit Property provides the human readable type of units that are displayed in the text area of the ScaleBar Control. It is not necessary that the MapUnit and DisplayUnit be the same on the ScaleBar. For example: the Map Controls SpatialReference may be in Decimal Degrees (a type of Geographic projection) but this might not serve as very useful for individuals using the map to view drive distances; setting the DisplayUnit to Miles would be more appropriate.

Types of DisplayUnit values:

The types of DisplayUnit values that can be set are defined in the ESRI.ArcGIS.Client.ScaleBarUnit Enumeration's. The availabe types are:

• Centimeters
• DecimalDegrees
• Decimteres
• Feet
• Inches
• Kilometers
• Meters
• Miles
• Millimeters
• NauticalMiles
• Undefined
• Yards