When None is selected, you will see all files when working with the isolated storage, and only files that have registered file extensions in external storage. InheritManifest , on the other hand, might be handy if you want to select a file from the isolated storage and limit the picker to files that are “pre-approved” in the manifest – obviously, this setting is unnecessary when handling external storage, since the policy is enforced by the OS by default. This property will not allow you to select files from external storage with extensions that have not been registered in the manifest.