In computing, external storage comprises devices that temporarily store information for transporting from computer to computer. Such devices are not permanently fixed inside a computer. External hard disk drives typically connect via USB; variants using USB 2.0 interface generally have slower data transfer rates when compared to internally mounted hard drives connected through SATA. Plug and play drive functionality offers system compatibility and features large storage options and portable design. As of March 2015, available capacities for external hard disk drives range from 500 GB to 8 TB.