Used Enterprise 3TB SAS HDD by Seagate. Tested and in working condition for server applications and computer hobbyist. Each drive comes with a hot swap chassis, equipped with a riser PCB so each hard drive can be easily inserted and removed from drive trays. Please note that these drives are SAS connectors, not SATA power/data. If you want to use these drives on a PC, they require an HBA card connected via Mini SAS 36 SFF-8087 to (4) SFF-8482 Connectors. All drives sector sizes are formatted to 520 for server environments. Upon request, I can format drive to 512 sector size for Windows 11 use.