Specially selected best quality low ash coal.Uses a Hi-tech manufacturing process.Even, fine and porous tissue structure assures its powerful chemical absorbing ability.Offers excellent chemical filtration ability to assure the safe and clear water quality.Chemical, Mechanical Dual stage filtration.Absorbs odors,discoloration,and toxins.For use in custom sumps / refugiums, hang-on filters, pre filter boxes, and more,Professional grade. Quick absorbing action with long term effectiveness.It can be cut to fit any size of your filter.