KB2 files are file system aware backups created by Kleo backup software. They are also referred to as hard drive images or "bare metal backups" since they contain full system backups. However, they do not include unused file system blocks, which significantly reduces the size of the backup file. The backups are further reduced by passing them through gzip (.GZIP) compression.

Since KB2 files contain an exact copies of hard disks, they may be used to perform complete system recoveries. Therefore, KB2 files are often used to backup and restore server hard drives.