I bought the SanDisk 1TB Extreme Pro to use as a back up drive with Time Machine. Unfortunately, after considerable time spent with Apple support and WD, I was never able to get this drive to work with Time Machine. I then decided to use the SanDisk as a clone drive. I could not get it to work as a clone drive with macOS using Apple Disk Utility. I then tried to use it as a clone drive using Super Duper!, which also did not work. I then tried ChronoSync ... also ends in an error. The physical size, amount of storage and speed of the SanDisk is great; but is of zero value for me as after weeks and weeks of trying I can't get it to work for what I need.