The PetSafe ScoopFree Premium Blue Crystal Litter 2 Pack comes with two pre portioned bags of our original scent crystal cat litter. 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 PetSafe ScoopFree reusable litter tray. When used with the PetSafe ScoopFree Self-Cleaning Litter Box and Reusable Litter Tray, one bag can last up to 30 days in a single cat household. PetSafe brand is here to help you and your pet live happy together. Tips For Maximizing the Life of Your Crystal Litter: 1) Place the litter box away from areas of high humidity, such as bathrooms, showers, and basements. Since the crystal litter controls odor by absorbing moisture, having extra moisture in the air will shorten the life of the tray. Try placing it in a room with moving air to pull away moisture, like a room with a fan. 2) If your cat consistently urinates in the same spot, try stirring the crystals occasionally to help distribute saturated crystals. 3) Cats with diets that are high in crude fiber and ash content will produce more solid waste, which can prematurely fill the waste trap. Consider changing your cat’s diet to a food with no byproducts or fillers.