They sit on them and eat their cereal, then run all night. I don't hear anything, and it is too small for a larger mouse, of which I have a larger mouse, I gave him this and he hated it. I give it 5 stars because my smaller mice love it! I really like these because they seem to be easy to clean, some vinegar and a cloth took care of the clean-up, wipe dry, put it back, happy mice 😁😊