Penn Plax Nitrate Remover Infused Filter Media Pad, 18 by 10-Inch FOR CRYSTAL CLEAR WATER: the filter media material helps maintain safe nitrate levels in your tank. MEASUREMENTS: made to be trimmed to fit your needs, the product is 10 x 18. MADE FOR ALL YOUR FILTRATION NEEDS: the filter media pad is made for freshwater and marine aquariums as well as ponds. FULL LINE OF MEDIA PADS AVAILABLE: sold on Amazon, there are activated carbon, ammonia remover, phosphate remover, polyfiber, and polyfiber plus pads, by Penn Plax. Each sold separately. SHOP PENN PLAX FOR ALL YOUR PETS NEEDS: Penn Plax is a manufacturer and distributer of top pet supplies, who specialize in creating excellent pet products for animals both great and small.