[StructLayout(LayoutKind.Sequential)] public class VOLUME_DETAILS_W { public const int MAX_PATH = 255; [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MAX_PATH)] public string PathName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst=100)] public string GUID; [MarshalAs(UnmanagedType.ByValTStr, SizeConst=50)] public string FSType; [MarshalAs(UnmanagedType.ByValTStr, SizeConst=100)] public string VolumeName; /*VOLUMETYPE Type; // Type of the volume (fixed, removable etc.)*/ public ulong BytesTotal; public ulong BytesFree; }