TranpoLine is one of Stick Michael's upgrades that prevents Big Blue from falling off of Stick Michael's line, instead, it makes him bounce at a lower height.
This upgrade can also be called as a "line ceiling", since that it prevents allies and enemies from surpassing it if they are below the line itself. While this is useful for keeping enemies away from Big Blue, it's a massive hindrance if Big Blue happens to be underneath the line.