Exton|OS build 150719 is based on Ubuntu 15.04 64 bit (released April 23, 2015) and Debian Jessie (Debian 8). Exton|OS’s ISO file is a ISO-hybrid, which means that it can very easily be transferred (copied) to a USB pen drive. You can then even run Exton|OS from the USB stick and save all your system changes on the stick. I.e. you will enjoy persistence! I’ve found two scripts which make the installation to USB very simple. The scripts are quite ingenious. My tests show that they work flawlessly...