My racks are custom made and my tubs fit snug in the racks. They don't have lids and make it easy for feeding and cleaning. All I have to do is slide out the tub and there it is! I use flexwatt on the back of the racks so that the back end of the tubs sit on the flexwatt which is powered by a thermostat. It works great and I've never had any of my snakes escape!