For over 30 years Good Pet Stuff Co. has been dedicated to creating top-notch pet products with a strong focus on uniqueness and innovation. Our Hidden Litter Box Planters have innovated the marketplace, and now we've designed new accessories to make life even easier! The 4-pack and 8-pack of square replacement carbon charcoal-infused odor filters fit perfectly into your Courtyard Hidden Litter Box Planters. Our Courtyard Hidden Litter Box Planter's 4-Pack of replacement filters are made from durable materials that can withstand the daily wear and tear from cats and other pets. They are infused with charcoal to increase odor-absorption capabilities, and thin enough for proper ventilation. These filters are thicker than others in the market, and are sunlight activated to ensure your home remains odor-free. As the original creators of the hidden litter box planter products, we take pride in providing our customers with top-quality and dependable pet products that make life with our furry friends a little easier. Check out our Amazon store for more pet products and other useful litter box accessories!