Mac OS X v10.5 (Leopard) introduced the concept of sparse-bundle disk images, where the data is stored as a collection of small, fixed-size band-files instead of as a single monolithic file. This allows for more efficient backups of the disk image, as only the changed bands need to be stored. One common source of sparse-bundles is Mac OS' backup utility, Time Machine, which stores the backup data within a sparse-bundle image on the chosen backup volume. This software package implements a FUSE virtual filesystem for read-only access to the sparse-bundle, as if it was a single monolithic image.