Provides support classes and delegates for the event-based asynchronous pattern. Developers should prefer the classes in the System.Threading.Tasks package. Commonly Used Types: System.ComponentModel.AsyncCompletedEventArgs System.ComponentModel.AsyncCompletedEventHandler System.ComponentModel.ProgressChangedEventArgs System.ComponentModel.ProgressChangedEventHandler System.ComponentModel.AsyncOperation System.ComponentModel.AsyncOperationManager When using NuGet 3.x this package requires at least version 3.4.