Yep. I know some don't agree with that but it's just until I can phase all the flexwatt stuff out. They are all 4" that are hooked to one thermostat though. I have some 11" on the 41qt tubs but they have a different thermostat. I monitor them all morning and evening with my temp gun, they are all within 1 degree of each other. And its only 4 shelves.