You can decorate an item with this attribute to indicate that it should provide a particular System.Drawing.Design.ToolboxItem . You can determine the type of the ToolboxItem with the ToolboxItemType property, and its name with ToolboxItemTypeName . You can compare against the Default and None values for equality. public class ToolboxItemAttribute : Attribute { // Public Constructors public ToolboxItemAttribute (bool defaultType ); public ToolboxItemAttribute (string toolboxItemTypeName ); public ToolboxItemAttribute (Type toolboxItemType ); // Public Static Fields public static readonly ToolboxItemAttribute Default ; // =System.ComponentModel.ToolboxItemAttribute public static readonly ToolboxItemAttribute None ; // =System.ComponentModel.ToolboxItemAttribute // Public Instance Properties public Type ToolboxItemType {get; } public string ToolboxItemTypeName {get; } // Public Instance Methods public override bool Equals (object obj ); // overrides Attribute public override int GetHashCode (); // overrides Attribute public override bool IsDefaultAttribute (); // overrides Attribute } HierarchySystem.Object System.Attribute ToolboxItemAttribute Valid OnAll |