The ScoopFree Premium Blue Crystal Litter 2-Pack comes with two pre-portioned bags of our original scent crystal litter without the disposable trays. The crystals absorb moisture on contact to quickly remove odors instead of masking them and can be used with any litter box or as refills for the ScoopFree Reusable Litter Tray. When used with the ScoopFree Self-Cleaning Litter Box and Reusable Litter Tray, one bag can last up to 30 days in a single-cat household.