Finnix is released as a small bootable CD ISO. A user can download the ISO, burn the image to CD, and boot into a text mode Linux environment. Finnix requires at least 32MiB RAM to run properly, but can use more if present. Most hardware devices are detected and dealt with automatically, such as hard drives, network cards and USB devices. A user can modify files nearly anywhere on the running CD via UnionFS, a filesystem that can stack a read-write filesystem (in this case, a dynamic ramdisk) on top of a read-only filesystem (the CD media). Any changes made during the Finnix session are transparently written to RAM and discarded upon shutdown. In addition, Finnix uses SquashFS to keep distribution size low.