The SelectionBoxTemplate is a ContentTemplate, not a Style. So if you wanted to present data in the selection box, you would basically have something like this:
The SelectionBoxTemplate is not predefined, you have to create it yourself and include the needed pieces of data. Please, check this online help article
on this topic.
If you wish to change appearance rather data, however, you need to customize the appearance of the RadComboBox control.
I hope this helps.
All the best,
the Telerik team
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