RadSlider can now be databound to a datasource. When you databind it, it automatically creates items and populates the Items collection. That is why to be able to databind RadSlider you should explicitly set ItemType="Item"
To control the databinding you should use the new ItemBinding inner property which provides the following properties:
TextField - determines which field of the datasource will be displayed as text of the item
ToolTipField - determines which field of the datasource will be displayed as tooltip of the item
ValueField - determines which field of the datasource will provide the value associated with the item
In addition, you can also add the databound items to already declared items by setting AppendDataBoundItems="true".