i used to have one so, persona experience here:
spend the extra 40 and get a johnson or ranco pre-wired from rich at www.reptilebasics.com. Literally, set it and forget it.
Even with that thing on i had UTH glass temps of 114 and that was REGULATED. Not cool zoomed, not cool. I could never get it to stabilize. If your room temps aren't exactly perfect all the time, its not going to do you a whole lot of good.