Blue Fine (High Density) Matala Mat Filter Pad 19" x 24"The open, highly aerobic 3 dimensional structure of Matala Filter Media promotes healthy water conditions and ease of cleaning in in a wide variety of filter designs.This is simply the most effective, longest lasting, crush resistant filter material available today! You"ll see it featured in every major Pond & Koi & Fish Care Magazine.It is a vast improvement over the OEM filter mats standard with most filters/skimmers today & a fantastic upgrade for any brand filter or skimmer!Easily trims to fit Aquascape, Savio, American, Easy Pro, Laguna, Cyprio/Hozelock, etc. skimmers & filters just to name a few.Features: A choice of densities allow for step-wise transition from mechanical to biological filtration Excellent surface area per sq. ft. with good adhesion of nitrifying bacteria. A high number of interstitial spaces in the tri-dimensional matrix of the filter media improves an early and even growth of bacteria.High free volume for smooth, even water flow throughout. Very resistant to plugging & easy cleaning.Mats are self-supporting, form-stable, rigid and non-brittle. Easy to cut to fit with Heavy duty Scissors, utility knife, circular saw or jig saw! Non-toxic to the environment. Light weight. Versatile and durable. Lasts for many years- 6+ (2-5 times longer than ANY other mat on the market!)1 1/2" ThickOTHER SIZES AVAILABLE!