4 Sheets 4 Color Matala Pond Filter Mat Koi Media Pad 12" X 12" FOR HEALTHY POND WATER AND EASY CLEANING: Green Vista's 4 Sheets 4 Colors Matala Pond Filter Mats Koi Media Pads promote healthy water conditions in a wide variety of filter designs. Lightweight and non-toxic to the environment, they feature an open, highly aerobic, 3 dimensional structure that results in smooth, even water flow throughout their material. They are very resistant to clogging and are simple to clean. Each of these 4 pads measures 12 inches by 12 inches. MOST EFFECTIVE, DURABLE AND CRUSH RESISTANT: This pond filter material is a vast improvement over filter mats that come with the majority of filters and skimmers. It is the most effective, longest lasting, crush resistant filter medium available. It can last over 6 years, 2 to 5 times longer than any other pond filter mat on the market! Its stable form is self-supporting, rigid and not brittle. EASY TO CUT TO SIZE: These pads can be trimmed easily to fit any skimmer or filter. Simply cut them to size by using heavy duty scissors, a utility knife, circular saw or jigsaw. DIFFERENT DENSITIES: Each of these four filter pads has a density different from the densities of the other three pads. Those density variations allow for a step-wise transition from mechanical to biological filtration in your water feature. LET GOOD BACTERIA FLOURISH: The excellent surface area per square foot of these mats allows beneficial bacteria to flourish. Good bacteria are essential to a healthy waterscape.