Telerik ASP.NET Calendar benefits from the ASP.NET AJAX framework to become an advanced date input control. Combining Date picker, Time picker and Date input, Telerik RadCalendar offers a myriad of features like adjacent months preview, multi-month view, context menus, etc. Its revolutionary rendering mechanism using CSS sprites guarantees fast loading time.

Features
Semantic Rendering for clean HTML
The Telerik ASP.NET Calendar implements a highly efficient semantic rendering, which results in minimum HTML output and dramatically improved performance.
Flexible client-side API
RadCalendar controls provide a flexible client-side API, allowing you to perform various operations on the client . You can easily interact with the controls in the browser using their client-side objects.
Various Customization Capabilities
The ASP.NET Calendar by Telerik provides a number of properties to let you customize the appearance of its elements, i.e. calendar title settings, navigations buttons, column and row headers, etc
Multiview Presentation
RadCalendar can be easily configured to show more than one month in the calendar area.
Template Support
RadCalendar allows you to define a collection of dynamic templates that customize the presentation of calendar days on a "per day" basis. The templates can contain regular HTML
Horizontal and Vertical Orientation
By default the Telerik ASP.NET AJAX Calendar view renders the days horizontally row by row. However, it can be configured to render the content vertically (i.e. column by column).
Keyboard Support
RadCalendar supports the standard browser navigation paradigm. Users can navigate across the page elements using the tab/shift/enter keys.
Product Screenshots

Telerik UI for ASP.NET AJAX Overview
Telerik UI for ASP.NET AJAX Calendar Demo
Telerik UI for ASP.NET AJAX Calendar Documentation