This app only works on Nexus 7 (2012 & 2013), Nexus 4 and Nexus 5, as they are the only devices officially supported by MultiROM.
This application requires root and it is designed to be used by experienced "power users". It is strongly recommended to read XDA thread before installing this app, you can find links at the bottom of this description.
MultiROM Manager can install or update MultiROM, it's recovery and kernels. It can also install Ubuntu Touch system-image based builds into MultiROM as a secondary ROM.
MultiROM is one-of-a-kind multi-boot mod for Nexus 7 (2012 and 2013), Nexus 4 and Nexus 5. It can boot any Android ROM as well as other systems like Ubuntu Touch. Besides booting from device's internal memory, MultiROM can boot from USB drive connected to the device via OTG cable. The main part of MultiROM is a boot manager, which appears every time your device starts and lets you choose ROM to boot. You can see how it looks on the left image below and in gallery. ROMs are installed and managed via modified TWRP recovery. You can use standard ZIP files to install secondary Android ROMs, daily prebuilt image files to install Ubuntu Touch and MultiROM even has its own installer system, which can be used to ship other Linux-based systems.
See XDA threads for more information:
Nexus 7 (2012): http://forum.xda-developers.com/showthread.php?t=2011403
Nexus 7 (2013): http://forum.xda-developers.com/showthread.php?t=2457063
Nexus 4: http://forum.xda-developers.com/showthread.php?t=2472295
Nexus 5: http://forum.xda-developers.com/showthread.php?t=2571011
Donate version: http://bit.ly/1nSnu2o
PayPal donations: http://bit.ly/mromdonations
Source code: https://github.com/Tasssadar/MultiROMMgr