At present, we don't provide a RadGauge control for ASP.NET AJAX.
Take a look at our Silverlight/WPF Gauge control as shown in the demos - http://demos.telerik.com/silverlight/#Gauge/Gallery/RadialScale
Additionally, you can review the following screencast:
which elaborates on the option to integrate Silverlight controls in your ASP.net Ajax application.
I hope this information helps.
the Telerik team
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