40 lb. bag is approximately a 20 week supply of healthy, biodegradable, all natural, 100% pure pine litter. The most effective cat litter you can buy! It's so effective you only need one inch. Feline Pine is made from selected, scrapped pine lumber. It is kiln-dried before processing and compressed into clean, sterile pellets that are 100% pure and natural. This pure pine litter naturally destroys odors. Chemical-free formula is environmentally compatible. The non-tracking formula is dust free, making it healthier for you and your cat. So healthy it's recommended for kittens and post-surgical cats. feline pine cat litter