Cheap internal storage: these are mechanical, spinning SATA hard disk drives (HDDs). There are two 2.5” (inch) thin, laptop compatible drives. Price, size, and performance characteristics vary per model. Good for adding or expanding internal storage capacity. Also great for local on-site and/or off-site data backups. All drives pass the Short DST diagnostic test. There are no known issues with any drive. I have securely wiped all data and formatted the drives with the NTFS file system, should be plug-n-play with any Windows computer. This collection of drives is from Western Digital (WD) and Toshiba.