This is a 64GB DDR4 ECC Registered DIMM validated for use in Synology's rack and tower NAS/SAN units that support memory expansion. ECC (error-correcting code) registered memory is used specifically because these units run as always-on storage servers handling live data integrity work - RAID/parity calculation, deduplication, caching, virtual machine hosting via Virtual Machine Manager - where an uncorrected memory bit-flip could silently corrupt stored data. IT administrators add modules like this to a Synology unit to raise its usable RAM ceiling for heavier workloads: larger read/write caches, more concurrent VMs or containers, or larger deduplication tables, rather than for general desktop or gaming use.