Matala Filter Sheet/Media Mat (Grey) 14" X 24" x 1.5" thick -For Koi Pond Filtration The open, highly aerobic 3 dimensional structure of Matala Filter Media promotes healthy water conditions. Gray Matala is the densest (finest) of the 4 standard colors of Matala Filter media. This is the most effective, longest lasting, crush resistant filter material available today. Versatile and durable. Lasts for many years -2-5 times longer. Measures: 14" x 24" x 1.5" thick