I used these for the filter in my pet turtle's tank. They absorb dirt and are easy to replace. I bought them in bulk, but I no longer need them, so I'm selling them. Replacement Filter Media: Activated Carbon Slim Mat x 1 Bacterial Slim Mat x 2 Each pack contains 3 pieces, for a total of 9 pieces. *Please use these with the following filter units:* ↓ Compatible Models: ● Slim Filter SS, S, M, L ● Aquarize ● Aqua 360R ● Silent Flow Slim I'm selling these at a low price to anyone who can use them. Thank you. *Please note: These have been stored at home for a long time.* *Please purchase only if you understand this.* *No claims or returns accepted.*