Tidy Cats Breeze Litter System (sold separately) uses specially-designed, cat-friendly litter pellets that allow urine to pass through, while leaving solid waste on top for quick, easy removal. The urine is quickly absorbed by these unscented odor-controlling pads for easy maintenance. Purina Tidy Cats BREEZE Cat Pads Refill for Multiple Cats 4 ct Pouch: Clean & easy disposable cat pads Absorb & control urine odor for up to one week (for one cat or 3 days for 2 cats) Unscented To be used with the Breeze Litter System, sold separatelyPurina