These Aquarium fine filter wool pads are among the highest quality on the market. These white filter wool pads can be cut to any size to suit any type of filter. Unlike cheaper wool on the market these pads are extremely high quality and will will not break down and perish in your filter. These aquarium wool pads are of such quality the can be washed and used over and over again. The fine fibres in these aquarium wool pads will trap the smallest of particles resulting in crystal clear water.