Don't trust your data on just any disk. Our disks are highly tested, Retail Box, Hot swap Drive assemblies, to add to or directly replace a failed 128420-B21, replacement part number 143916-001 for select Compaq ProLiant servers with card edge drive storage backplanes. Our drives are Very Low Power, faster, state-of-the-art design, of new manufacture (not old stock, not refurbs, not 90 day units, not bulk packaged like the other sellers) This drive is more reliable than the original. Uses Only 12 watts! This drive is NOT Universal. 36.4GB 10,000RPM Low Profile (STD 1.6" Opt 1") Hot Swap Drive has a 4MB Cache and a Ultra320, Ultra160, Ultra3 and Ultra2 interface compatible with all HP/Compaq Proliant Servers listed below. Formatted Capacity: 36.7GB Compression: (Native/Uncompressed) Data Storage Device Type: SAS (Server Attached Storage) device Hard Drive Device Type: Internal hard drive Interface Type: 80-pin Ultra 160 SCSI Interface: Ultra, Ultra2, Ultra3, Ultra160, Ultra320, Wide SCSI Formatted Internal Transfer Rate (Min.): 26.7MB/sec Formatted Internal Transfer Rate (Max.): 40.2MB/sec External I/O Transfer Rate (Max.): 320MB/sec Average Seek Time Read: 5.2ms typical Default Buffer: 4MB Spindle Speed: 10033 RPM MTBF: 1,200,000 hours S.M.A.R.T. Support: Yes Warranty: 3-year Compatibility: Proliant Models: Storage System/U, 7000, 6500, 6000, 5500, 300, 1850r(450 & Below) and 850r. Other Proliants with card edge backplane but speeds may vary due to lack of Ultra2/3 controllers. Also available in 72MB , 147GB and 300GB Versions! 15,000 RPM Option Available! Availability: Usually ships the next business day. 128420-b21 o$278.45Options: No Options15,000 RPM (+109)