This Carbon Filter Pad is a dense chemical filter pad designed to absorb dissolved organic matter, remnants of medications, and tannins from, for example, driftwood. It also facilitates the removal of particulates, odors, and discoloration from your aquarium system. This Filter Pads can be cut and shaped to fit any filtration system, such as: Canister Filters, Hang-On Filters, Trickle Filters, Pond Filters, Wet/Dry Filters, Filter Cartridge Frames, and any other application where mechanical and chemical filtration is needed. Great for both freshwater and marine applications. It measures 18" x 10".