Compatible Models: This carbon filter is designed for litter-robot 4, on the other hand not be too thick to make the machine malfunction. High Quality Material: Our litter robot 4 filter is made of high quality powdered activated carbon as adsorption material, which has good adsorption and dust collection effect, and can be cut and folded arbitrarily, and it is non- and odorless, which is very safe for pets. Purify the Air: Our litter robot 4 carbon filters can effectively control the moisture on the pet, reduce the odor in the cat litter box, so that you are no longer troubled by the unpleasant odor of pet excrement, have a fresher . Easy to Use: When you need to replace the filter, just open the lid, remove the old filter cotton and replace it with a new one. we recommend you to change the filters at least once a month, so you can use it for about 8 months, enjoy your fresher ! Color: Black Material: Sponge Package Contents: 10 Pack * Carbon Filters Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.