# Key Features

Develop powerful and lightweight web applications using ASP.NET MVC controls. Learn more about the ComponentOne MVC controls in ASP.NET MVC documentation.

## Content

ComboBox also offers many advanced features. These features are listed below:

* [SelectedItem](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedItem.html)
    Represents the currently selected item in the drop-down list.
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* [SelectedIndex](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedIndex.html)
    Represents the index of the [SelectedItem](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedItem.html) in the drop-down list.
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* [SelectedValue](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedValue.html)
    Represents the value of the [SelectedItem](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedItem.html), obtained using the SelectedValuePath.
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* [SelectedValuePath](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedValuePath.html)
    Represents the name of the property used to get the [SelectedValue](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedValue.html) and [SelectedItem](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.SelectedItem.html).
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* [MaxDropDownHeight](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.MaxDropDownHeight.html)
    Set the value of the [MaxDropDownHeight](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.MaxDropDownHeight.html) property to set the maximum height of the drop-down list.
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* [MaxDropDownWidth](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.MaxDropDownWidth.html)
    Set the value of the [MaxDropDownWidth](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.MaxDropDownWidth.html) property to set the maximum width of the drop-down list.
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* [IsEditable](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.IsEditable.html)
    Determines whether a user can enter values that do not appear on the ComboBox's item list.
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* [VirtualizationThreshold](/componentone/api/mvc/online-mvc/dotnet-framework-api/C1.Web.Mvc/C1.Web.Mvc.ComboBoxBase-1.VirtualizationThreshold.html)
    Use the **VirtualizationThreshold** property to set the minimum number of rows and/or columns required to enable virtualization in the ComboBox control. For more information, see [Virtualization](/componentone/docs/mvc/online-mvc/workwithcontrols/Input/InputCommonFeatures/input-virtualization).

## Key Actions

| Property | Values | Description |
| -------- | ------ | ----------- |
| key-action-print-characters | ChangeSelectionOnly / OpenDropdown | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• Type to select matching options without opening the dropdown.</span><br><br><span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• Dropdown opens automatically when typing starts.</span> |
| <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">key-action-down-arrow</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">ChangeSelectionOnly / OpenDropdown</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• Navigate options with arrow keys.</span><br><br><span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• Opens dropdown when using arrow keys if it is closed.</span> |
| <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">key-action-up-arrow</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">ChangeSelectionOnly / OpenDropdown</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">Same behavior as down arrow.</span> |
| <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">key-action-tab</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">CloseAndKeepFocus / CloseAndMoveFocus</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• CloseAndKeepFocus: Dropdown closes, focus stays on control.</span><br><br><span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">• CloseAndMoveFocus: Dropdown closes and focus moves forward.</span> |
| <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">aria-labelled-by</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">User-defined</span> | <span class="cf0" style="box-sizing: content-box; margin: 0px; padding: 0px; transition: filter 0.5s ease-in-out; line-height: 25.6px;">Defines an ARIA label reference for screen readers to describe the control.</span> |