I have a few of these racks for my adults. On some of them i use one 11" heat pad on each shelf (pictured).. I also use large caster wheels so i can roll them around easily when needed. Doing this adds $50 to the cost of the rack but it's worth it.
I make some racks with one long strip of 3" heat tape for the whole rack, it is easier to intall the 3" tape and cheaper because i only need one clip set. But, once completed i really like the 11" better for my larger animals and I can unplug the unused levels when bins are empty.(NOTE: this rarely happends)
~ Mike
