RadCombobox value when choosing vs Expand

I have a combobox with values ​​0, 1, 2. When the user expands the combo box to select a value, I want to show the value text as 0 - Bad, 1 - Average, 2 - Good.

But when the user selects a value, I only want to show that value.

How can i do this? Here is my code

 <telerik:RadComboBox ItemsSource="{Binding Flags}"
                            SelectedValue="{Binding FlagId,Mode=TwoWay}"
                            SelectedValuePath="Id"
                            DisplayMemberPath="Id">               
 </telerik:RadComboBox>