Ok. I've been holding it off for some time but I'm looking into getting a rack system. Since I started out with glass tanks then gradually switched over to tubs. I was always under the impression that the Under Tank Heater is not to take up nomore than half of the enclosures floor space roughly 1/4, so if I had a 36" long enclosure I would use something around 11x11". My question is why is it that I only come across racks with 3" and 4" belly heat. Are there any rack systems which offer a wider heating area like using a 11" piece of flexwatt, by the way I'm looking into a rack that holds the sterilite 41qt tubs. I'd like to have a wider area of coverage for my female balls and sub adult male boas.