xThe Break Inx were a straight-edge band from Kent, UK. They played in your face heavy hardcore central to the ideas and messages of a straight-edge lifestyle. A few members of the band are currently playing in Inherit, (along with members of Pain Runs Deep, Never X Again and several other bands) and Unholy Majesty. As for the name of this demo, it obviously means Demo 2003, however a thousand would be indicated by "K" not, "X", that means ten. However, they're a straight-edge band, so I'm guessing it's deliberate. They also brought out some later releases, of a much more musically advanced and better produced and mixed sound, including "Unbowed" which can be downloaded here (I found this link online, it's not my upload) and another EP.
(This download also includes the lyric sheet).