Seagate Exos X20z 18TB (ST18000NM013J) host-managed SMR enterprise SATA III hard drive. The drive label reads "HSMR: 18TB", "Exos X20z" and "20TB Avg HSMR" - this is the X20z host-managed SMR platform, not the conventional (CMR) Exos X18. Pulled from a decommissioned storage array, tested and working. Power-on hours: 34,256 across the pool (see SMART screenshots). SMART overall health: PASSED on every unit, 0 reallocated sector(s), 0 pending sector(s). This listing covers 5 equivalent drives. You will receive ONE drive from the pool below. Every unit has been individually SMART-tested and photographed, and all fall within the hour range stated in the title: S/N ZR570HCD - 34,256 hours S/N ZR570SDB - 34,256 hours S/N ZR5710DA - 34,256 hours S/N ZR571QSA - 34,256 hours S/N ZR56Z3N8 - 34,256 hours Condition: Used - fully functional, minor cosmetic wear from rack use. No physical damage. IMPORTANT - this is a Host-Managed SMR (HSMR) drive, confirmed on the drive label (see photos). Host-managed SMR needs an SMR-aware host: it will NOT drop into a normal desktop, hardware RAID array or standard ZFS/NTFS pool the way a CMR drive does. Please confirm your stack supports HM-SMR (ZBD/zoned block devices) before buying. What's included: drive only (no cables/screws unless stated). Please review the SMART screenshot for full drive history before buying - happy to answer questions about the source system. Photos show a representative drive from the pool. Every drive's individual SMART data is listed above, and the drive you receive will be one of them.