SlackBuildsOrg/system/squashfs-tools

Squashfs is a compressed read-only filesystem for Linux. Squashfs is intended
for general read-only filesystem use, for archival use (i.e. in cases where a
.tar.gz file may be used), and in constrained block device/memory systems
(e.g. embedded systems) where low overhead is needed.

Compiles support for gzip, xz (default), lzo, and lzma compression.