BusyBox combines tiny versions of many common UNIX utilities into a
single small executable.

It provides replacements for most of the utilities you usually find in
GNU fileutils, shellutils, etc. The utilities in BusyBox generally have
fewer options than their full-featured GNU cousins; however, the
options that are included provide the expected functionality and behave
very much like their GNU counterparts. BusyBox provides a fairly
complete environment for any small or embedded system.

The SlackBuilds version is built statically, with near-vanilla configs.

If you wish to customize the build, you can place your custom BusyBox
build ".config" file in the SlackBuild directory with the file name
"build-config" before executing the SlackBuild script.  The script will
pick the "build-config" file up and use it instead of the default one.