You can use this 500 GB, 7200 rpm SATA E-DDM (part number 39M4554) in DS4700 Express Models 70 and 72 and EXP810 Storage Expansion Units. Up to 16 SATA E-DDMs can be supported in each enclosure, providing a physical storage capacity of up to 8 TB per enclosure.Using the 500 GB SATA E-DDM, you can build DS4700 storage configurations of up to 56 TB, and DS4800 storage configurations of up to 112 TB. The 500 GB SATA E-DDM enables alternative, and more economical, DS4700 and DS4800 storage configurations to meet the large-capacity needs of data reference or fixed content types of applications.