The SDX5400W is an AIT tape by Sony. To be specific, the SDX5400W is an a href="http://www.tape4backup.com/ait-5-tapes.php">AIT-5 tape by Sony and is a W.O.R.M (Write Once Read Many) tape. This means that data written on the SDX5400W the first time cannot be deleted but may only be added two, hence it can only be written on once but read many times. W.O.R.M tapes are particularly useful for archival storage. An example of archival storage may be where old copies of the newspaper are stored in libraries for future viewing. The data, in this case the copy of the old newspapers on a tape such as the SDX5400W, will not really need to be changed once it has been written onto a tape but is only required for viewing. The Sony SDX5400W tape has a capacity of 400 GB native and 1040 GB of compressed data storage. The transfer rate applicable for the SDX5400W tape is 24 MB/s and the Sony SDX5400W also features an R-MIC (Remote - Memory In Cassette) that stores specific drive and media formats and statistics. It also allows the AIT drive to load and search much faster than would otherwise be possible. AIT-4 and AIT-5 products available at Tape 4 Backup: By Product Part Number: 1.) SDX4-200C 2.) SDX5-400C 3.) SDX5400W By Product Name: 1.) Sony AIT-4 Data Cartridge 200/520 GB 2.) Sony AIT-5 Data Cartridge 400/1040 GB 3.) Sony AIT-5 Data Cartridge 400/1040 GB