I use those shelves for my sub-adult rack. I changed the height of the shelves to accomodate the height of my 16qt tubs. I have 2 of these shelving units holding 16 of these tubs. I am also considering making plastic dividers for the 16 tubs to split them lengthwise while keeping the depth to the heat tape at the back for future babies since I cant afford the exact hatchling rack that I want yet.