1 Sheet Matala Pond Grey Filter Mat Koi Media Pad 19" X 24" The open, highly aerobic 3 dimensional structure of Matala Filter Media promotes healthy water conditions and ease of cleaning in a wide variety of filter designs. Provides ease of cleaning in a wide variety of filter designs. Gray Matala is the finest (densest) of the 4 standard colors of Matala Filter media. Versatile and durable. Lasts for many years -2-5 times longer than other media. Measures: 19" x 24" x 1.5" thick.