This thesis is about register and how it affects my playing through compositions and improvisation. As a brass musician, the high and low range is something that takes a lot of effort to master. How important is register for my artistic expression and how does register influence my music?  My method to test this is by composing with a template where I have three musical components that I arrange in different registers. The first component is melody. The second one is ostinato, which in this thesis means something rhythmical that creates movement through time. The last component is harmony.  In the next part of the thesis, I analyze all of my compositions and describe how I have worked with the template. I have also written about what difficulties we encountered as a band when we rehearsed the music. The band consists of me on trombone and bass trombone, Olle Vikström on tenor and baryton saxophone, Sara Karkkonen on piano, Johan Tengholm on bass and Henrik Jäderberg on drums. In the end of this thesis I discuss how register have influenced how the components work together like the clarity of the melody and how the harmony is affected by the melody.I find the instrumentation is of higher influence than the register but this specific constellation of instruments may have influenced how I perceive the components.