This product is the Gray Matala Filter Pad for the Medium Aquafalls. Gray is finest pad and used for lower flow rates where complete debris removal is needed. This Medium AquaFalls Pad is shaped like a trapezoid, measuring 23.5" long on one end, 20.5" long on the other and 30" wide. 3 pads per Aquafalls are required. You can mix Green, Blue and Gray for best filtration results, but have the water go through the coarsest pad first.