GENERIC 4TB 3.5,MaxDigital 4TB 7200RPM 64MB Cache SATA III 6.0Gb/s (Enterprise Storage) 3.5,Hitachi 4TB 3.5in SAS Hard Drive HUS724040ALS640,Western Digital RED WD40EFRX 4TB 64MB Cache 3.5,MaxDigital 4TB 7200RPM 64MB Cache SATA III 6.0Gb/s (Enterprise Storage) 3.5