Cygnos360 is a Modchip that allows you to have more than one kernel version on your xbox 360. Currently users can only have either a vulnerable kernel version (4532 or 4548) OR the current kernel version that is neccessary to use xbox live and play the newest games. Cygnos360 enables you to conveniently switch between your "live kernel" and your "homebrew kernel".
You can also use Cygnos360 to switch between PAL and NTSC kernels.
NOTE: Cygnos360 does not contain any kernel image! It is shipped empty! Cygnos360 does NOT enable "backups" it is NOT for the DVD drive. You need to have an infectus programmer or another programmer to flash the Cygnos360.