Disk drives are available in A grade or B grade, whilst B grade is sometimes fine for PC's which use full formatting and identify bad sectors etc
DVR's usually use a fast format technique, which does NOT identify BAD sectors, so a disk failure is far more likely, meaning the installer is far more likely to have to re-visit under a warranty claim! We consider this too high risk for the "price difference!!"
Please Note: Not only do we only supply A grade Disks made by Western Digital! the SA machines allow a Full Format option.
WE DON'T SUPPLY CHEAP "B" GRADE DRIVES or machines that cant be fully formatted!!!