it the spending about 7-8 bucks for the tubs that giving me fits. The only space between the tubs and th framming is on the middle row ( I got them set up as a side by side ( might be the problem) )set up since Mom likes to give them treats and they too much for her high up when she in her wheelchair. My chewers seem to be the new rats I get and i need so many small ones I can't toss or feed off a breeder when they finally producing for me lol ( went 3 months with no productiong and it killed me I need this rack system to work out so Ican rotate the breeding ages .