public const int IOCTL_STORAGE_GET_DEVICE_NUMBER = 0x2D1080;

     if (DeviceIoControl(h, IOCTL_STORAGE_GET_DEVICE_NUMBER, IntPtr.Zero, 0, ptrSdn, nBytes, out requiredSize, IntPtr.Zero))

const int IOCTL_STORAGE_GET_DEVICE_NUMBER = 0x2D1080;

Const IOCTL_STORAGE_GET_DEVICE_NUMBER As Integer = &H2D1080