Thanks for contacting us.
Since Q3 2010 the easiest way to change the version of the Telerik controls in the toolbox is using the Toolbox Configurator. It can be launched from the Telerik menu, RadControls for WinForms -> Launch Toolbox Configurator.
If the version of your Visual Studio Extensions is older than Q3 2010, please refer to the following article - Adding RadControls to Visual Studio Toolbox
I hope this will help.
the Telerik team
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