ITEM NAME:Media Two Layers Cotton Pad Mat Foam Sponge for Aquarium Fish Tank S9F9 Z2Z U4H7 HOT SALE body .shopclass { float: left; width: 100%;.This product is suitable for sea water cylinder, fresh water tank, water straw cylinder, size can be freely cut. Biochemical cotton is used to decompose waste and feed residue and improve water quality filtration.